Naval mine A naval mine is a self - contained explosive device placed in water to destroy surface ships or submarine s . Unlike depth charge s , mines are deposited and left to wait until they are triggered by the approach of , or contact with , an enemy vessel . Naval mines can be used offensively — to hamper enemy shipping movements or lock vessels into a harbour ; or defensively — to protect friendly vessels and create " safe " zones . Description . Mines can be laid in many ways : by purpose - built minelayer s , refitted ships , submarines , or aircraft — and even by dropping them into a harbour by hand . They can be inexpensive : some variants can cost as little as US $ 1000 , though more sophisticated mines can cost millions of dollars , be equipped with several kinds of sensors , and deliver a warhead by rocket or torpedo . Their flexibility and cost - effectiveness make mines attractive to the less powerful belligerent in asymmetric warfare . The cost of producing and laying a mine is usually anywhere from 0 . 5 % to 10 % of the cost of removing it , and it can take up to 200 times as long to clear a minefield as to lay it . Parts of some World War II naval minefields still exist because they are too extensive and expensive to clear . It is possible for some of these 1940s - era mines to remain dangerous for many years to come . Mines have been employed as offensive or defensive weapons in rivers , lakes , estuaries , seas , and oceans , but they can also be used as tools of psychological warfare . Offensive mines are placed in enemy waters , outside harbours and across important shipping routes with the aim of sinking both merchant and military vessels . Defensive minefields safeguard key stretches of coast from enemy ships and submarines , forcing them into more easily defended areas , or keeping them away from sensitive ones . Minefields designed for psychological effect are usually placed on trade route s and are used to stop shipping reaching an enemy nation . They are often spread thinly , to create an impression of minefields existing across large areas . A single mine inserted strategically on a shipping route can stop maritime movements for days while the entire area is swept . International law requires nations to declare when they mine an area , in order to make it easier for civil shipping to avoid the mines . The warnings do not have to be specific ; for example , during World War II , Britain declared simply that it had mined the English Channel , North Sea , and French coast . History . Early use . The precursor to naval mines was first described by the early Ming Dynasty Chinese artillery officer Jiao Yu , in his 14th century military treatise known as the " Huolongjing " . Chinese records tell of naval explosives in the 16th century , used to fight against Japanese pirates ( Wokou ) . This kind of naval mine was loaded in a wooden box , sealed by putty . General Qi Jiguang made several timed , drifting explosives to harass Japanese pirate ships . However , in the " Tiangong Kaiwu " ( ' The Exploitation of the Works of Nature ' ) treatise , written by Song Yingxing in 1637 AD , it describes naval mines with a rip cord pulled by hidden ambushers located on the nearby shore who rotated a steel wheellock flint mechanism to produce sparks and ignite the fuse of the naval mine . Although this is the rotating steel wheellock ' s first use with naval mines , Jiao Yu had described their use for land mine s back in the 14th century . The first plan for a sea mine in the West was by Ralph Rabbards , who presented his design to Queen Elizabeth I of England in 1574 . The Dutch inventor Cornelius Drebbel was employed in the Office of Ordnance by King Charles I of England to make weapons , including a " floating petard " which proved a failure . Weapons of this type were apparently tried by the English at the Siege of La Rochelle in 1627 . American David Bushnell invented the first practical mine , for use against the British in the American War of Independence . It was a watertight keg filled with gunpowder that was floated toward the enemy , detonated by a sparking mechanism if it struck a ship . It was used on the Delaware River as a drift mine , and was regarded as unethical . 19th century . In 1812 Russian engineer Pavel Shilling exploded an underwater mine using an electrical circuit . In 1854 , during the unsuccessful attempt of the Anglo - French fleet to seize Kronshtadt fortress , British steamships HMS " Merlin " ( 9 June 1855 , the first successful mining in history ) , HMS " Vulture " and HMS " Firefly " were damaged by underwater explosions of Russian naval mines . More than 1500 naval mines , or " infernal machines " , designed by Moritz von Jacobi and Alfred Nobel were set by Russian naval specialists in the Gulf of Finland during the Crimean War . The mining of " Vulcan " led to the world ' s first minesweeping operation . During the next 72 hours , 33 mines were swept . The American Civil War also saw the successful use of mines . The first ship sunk by a mine was the USS " Cairo " in 1862 in the Yazoo River . Rear Admiral David Farragut ' s famous statement , " Damn the torpedoes , full speed ahead ! " refers to a minefield laid at Mobile , Alabama . In the 19th century , mines were called torpedo es , a name probably conferred by Dennis Fletcher after the torpedo fish , which gives powerful electric shock s . A spar torpedo was a mine attached to a long pole and detonated when the ship carrying it rammed another one . The " H . L . Hunley " used one to sink the USS " Housatonic " on February 17 , 1864 . A Harvey Torpedo was a type of floating mine towed alongside a ship , and was briefly in service in the Royal Navy in the 1870s . Other " torpedoes " attached to ships or propelled themselves . One such weapon , called the Whitehead torpedo after its inventor , caused the word " torpedo " to be used for self - propelled underwater missiles as well as static devices . These mobile devices were also known as " fish torpedos . " Following the Civil War , the United States adopted the mine as its primary weapon for coast defense . In the decade following 1868 , Maj . Henry Larcom Abbot carried out a lengthy set of experiments to design and test moored mines that could be exploded on contact or be detonated at will as enemy shipping passed near them . This initial development of mines in the United States took place under the purview of the U . S . Army Corps of Engineers , which trained officers and men in their use at the Engineer School of Application at Willets Point , NY ( later the site of Fort Totten ) . Early 20th century . During the Boxer Rebellion , Imperial Chinese forces deployed a command - detonated mine field at the mouth of the Peiho river before the Dagu forts , to prevent the western Allied forces from sending ships to attack . The next major use of mines was during the Russo - Japanese War of 1904 - 1905 . They proved their worth as weapons in this conflict . For instance , two mines blew up when the Russian battleship " Petropavlovsk " struck them near Port Arthur , sending the holed vessel to the bottom and killing the fleet commander , Admiral Stepan Makarov , and most of her crew in the process . The toll inflicted by mines was not confined to the Russians , however . The Japanese Navy lost two battleships , four cruisers , two destroyers and a torpedo - boat to offensively laid mines during the war . Most famously , on May 15 , 1904 , the Russian minelayer " Amur " planted a 50 - mine minefield off Port Arthur and succeeded in sinking the Japanese battleships " Hatsuse " and " Yashima " . Many early mines were fragile and dangerous to handle , as they contained glass containers filled with nitroglycerin or mechanical devices that activated a blast upon tipping . Several mine - laying ships were destroyed when their cargo exploded . Beginning around the start of the 20th century , submarine mines played a major role in the defense of U . S . harbors against enemy attack . The mines employed were controlled mines , anchored to the bottoms of the harbors and detonated under control from large mine casemates on shore . During World War I , mines were used extensively to defend coasts , coastal shipping , ports and naval bases around the globe . The Germans laid mines in shipping lanes to sink merchant and naval vessels serving Britain . The Allies targeted the German U - boats in the Strait of Dover and the Hebrides . In an attempt to seal up the northern exits of the North Sea , the Allies developed the North Sea Mine Barrage . During a period of five months from June almost 70 , 000 mines were laid spanning the North Sea ' s northern exits . The total number of mines laid in the North Sea , the British East Coast , Straits of Dover , and Heligoland Bight is estimated at 190 , 000 and the total number during the whole of WWI was 235 , 000 sea mines . Clearing the barrage after the war took 82 ships and 5 months , working around the clock . World War II . During World War II , the U - boat fleet , which dominated much of the battle of the Atlantic , was small at the beginning of the war and much of the early action by German forces involved mining convoy routes and ports around Britain . German submarines also operated in the Mediterranean Sea , in the Caribbean Sea , and along the U . S . coast . Initially , contact mines — requiring a ship physically strike a mine to detonate it — were employed , usually tethered at the end of a cable just below the surface of the water . Contact mines usually hole ships ’ hulls . By the beginning of World War II , most nations had developed mines that could be dropped from aircraft and floated on the surface , making it possible to lay them in enemy harbours . The use of dredging and nets was effective against this type of mine , but this consumed valuable time and resources , and required harbours to be closed . Later , some ships survived mine blasts , limping into port with buckled plates and broken backs . This appeared to be due to a new type of mine , detecting ships magnetically and detonating at a distance , causing damage with the shock wave of the explosion . Ships that had successfully run the gauntlet of the Atlantic crossing were sometimes destroyed entering freshly cleared British harbours . More shipping was being lost than could be replaced , and Churchill ordered the intact recovery of one of these new mines to be of the highest priority . The British experienced a stroke of luck in November 1939 . A German mine was dropped from an aircraft onto the mud flats of the Thames estuary during low tide . As if this was not sufficiently good fortune , the land belonged to the army , and a base with men and workshops was at hand . Experts were dispatched from London to investigate the mine . They had some idea that the mines used magnetic sensors , so everyone removed all metal , including their buttons , and made tools of non - magnetic brass . They disarmed the mine and rushed it to labs at Portsmouth , where scientists discovered a new type of arming mechanism . A large ferrous object passing through the Earth ' s magnetic field will concentrate the field through it ; the mine ' s detector was designed to trigger at the midpoint of a steel - hulled ship passing overhead . The mechanism had an adjustable sensitivity , calibrated in milligauss . ( As it turned out , the German firing mechanism was overly sensitive , making sweeping easier . ) The U . S . began adding delay counters to their magnetic mines in June 1945 . From these data , methods were developed to clear the mines . Early methods included the use of large electromagnets dragged behind ships or below low - flying aircraft ( a number of older bombers like the Vickers Wellington were used for this ) . Both of these methods had the disadvantage of " sweeping " only a small strip . A better solution was found in the " Double - L Sweep " using electrical cables dragged behind ships that passed large pulses of current through the seawater . This induced a large magnetic field and swept the entire area between the two ships . The older methods continued to be used in smaller areas . The Suez Canal continued to be swept by aircraft , for instance . Wartime Japanese sweep methods , by contrast , never advanced much past 1930s standards , and failed entirely to keep up with new American mines , clearing no more than 15 % of all the mines laid in Japan ' s coastal waters . Moreover , IJN ' s minesweeping force was far too small with 350 ships , and 20 , 000 men . While these methods were useful for clearing mines from local ports , they were of little or no use for enemy - controlled areas . These were typically visited by warships , and the majority of the fleet then underwent a massive degaussing process , where their hulls had a slight " south " bias induced into them which offset the concentration effect almost to zero . Initially , major warships and large troopships had a copper " degaussing coil " fitted around the perimeter of the hull , energized by the ship ' s electrical system whenever in suspected magnetic - mined waters . Some of the first to be so - fitted were the carrier HMS " Ark Royal " and the liners and , which were used as troopships . This was felt to be impracticable for the myriad of smaller warships and merchant vessels , not least due to the amount of copper that would be required . It was found that " wiping " a current - carrying cable up and down a ship ' s hull temporarily cancelled the ships ' magnetic signature sufficiently to nullify the threat . This started in late 1939 , and by 1940 merchant vessels and the smaller British warships were largely immune for a few months at a time until they once again built up a field . Many of the boats that sailed to Dunkirk were degaussed in a marathon four - day effort by degaussing stations . The Allies deployed acoustic mines , against which even wooden - hulled ships ( in particular minesweeper s ) remained vulnerable . Japan developed sonic generators to sweep these ; the gear was not ready by war ' s end . The primary method Japan used was small air - delivered bombs . This was profligate and ineffectual ; used against acoustic mines at Penang , 200 bombs were needed to detonate just 13 mines . The Germans had also developed a pressure - activated mine and planned to deploy it as well , but they saved it for later use when it became clear the British had defeated the magnetic system . The U . S . also deployed these , adding " counters " which would allow a variable number of ships to pass unharmed before detonating . This made them a great deal harder to sweep . Japan ' s antiquated sweep methods , lifting mines in nets , accidentally proved useful against these mines ; it remained too slow and hazardous to be truly effective , especially in light of the high numbers being laid . Mining campaigns could have devastating consequences . The U . S . effort against Japan , for instance , closed major ports , such as Hiroshima , for days , and by the end of the Pacific War had cut the amount of freight passing through Kobe – Yokohama by 90 % . When the war ended , more than 25 , 000 U . S . - laid mines were still in place , and the Navy proved unable to sweep them all , limiting efforts to critical areas . After sweeping for almost a year , in May 1946 , the Navy abandoned the effort with 13 , 000 mines still unswept . Over the next thirty years , more than 500 minesweepers ( of a variety of types ) were damaged or sunk in continuing clearance efforts . Cold War era . Since World War II , mines have damaged 14 United States Navy ships , whereas air and missile attacks have damaged four . During the Korean War , mines laid by North Korean forces caused 70 % of the damage suffered by U . S . naval vessels and caused 4 sinkings . During the Iran – Iraq War from 1980 to 1988 , the belligerents mined several areas of the Persian Gulf and nearby waters . On April 14 , 1988 , the USS " Samuel B . Roberts " ( FFG - 58 ) struck an Iranian M - 08 / 39 mine in the central Persian Gulf shipping lane , wounding 10 sailors . In the summer of 1984 , magnetic sea mines damaged at least 19 ships in the Red Sea . The U . S . concluded Libya was probably responsible for the minelaying . In response the U . S . , Britain , France , and three other nations launched Operation Intense Look , a minesweeping operation in the Red Sea involving more than 46 ships . On the orders of the Reagan administration , the CIA mined Nicaragua ' s Sandino port in 1984 in support of the Contra guerrilla group . A Soviet tanker was among the ships damaged by these mines . In 1986 , in the case of " Nicaragua v . United States " , the International Court of Justice ruled that this mining was a violation of international law . During the Gulf War , Iraqi naval mines severely damaged USS " Princeton " ( CG - 59 ) and USS " Tripoli " ( LPH - 10 ) . When the war concluded , eight countries conducted clearance operations . Types . Naval mines may be classified into two major groups . Contact mines . The earliest mines were usually of this type . They are still used today , as they are extremely low cost compared to any other anti - ship weapon and are effective , both as a terror weapon and to sink enemy ships . Contact mines need to be touched by the target before they detonate , limiting the damage to the direct effects of the explosion and usually affecting only the single vessel that triggers them . Early mines had mechanical mechanisms to detonate them , but these were superseded in the 1870s by the Hertz Horn ( or chemical horn ) , which was found to work reliably even after the mine had been in the sea for several years . The mine ' s upper half is studded with hollow lead protuberances , each containing a glass vial filled with sulfuric acid . When a ship ' s hull crushes the metal horn , it cracks the vial inside it , allowing the acid to run down a tube and into a lead - acid battery which until then contains no acid electrolyte . This energizes the battery , which detonates the explosive . Earlier forms of the detonator employed a vial of sulfuric acid surrounded by a mixture of potassium perchlorate and sugar . When the vial was crushed , the acid ignited the perchlorate / sugar mix , and the resulting flame ignited the gunpowder charge . During the initial period of World War I , the British Navy used contact mines in the English Channel and later in large areas of the North Sea to hinder patrols by German submarine s . Later , the American antenna mine was widely used because submarines could be at any depth from the surface to the seabed . This type of mine had a copper wire attached to a buoy that floated above the explosive charge which was weighted to the seabed with a steel cable . If a submarine ' s steel hull touched the copper wire , the slight voltage change caused by contact between two dissimilar metals was amplified and detonated the explosives . Limpet mines . Limpet mines are a special form of contact mine that are manually attached to the target by magnets and left , and are so named because of the superficial similarity to the limpet , a mollusk . Moored contact mines . Generally , this mine type is set to float just below the surface of the water or as deep as five meters . A steel cable connecting the mine to an anchor on the seabed prevents it from drifting away . The explosive and detonating mechanism is contained in a buoyant metal or plastic shell . The depth below the surface at which the mine floats can be set so that only deep draft vessels such as aircraft carriers , battleships or large cargo ships are at risk , saving the mine from being used on a less valuable target . In littoral waters it is important to ensure that the mine does not become visible when the sea level falls at low tide , so the cable length is adjusted to take account of tides . Even during the Second World War , there were mines that could be moored in 300m - deep water ( Example : The U . S . Mark 6 ) . Floating mines typically have a mass of around 200 kg , including 80 kg of explosives e . g . TNT , minol or amatol . During WWII mine traps were used for blocking port entrances . Two floating mines were anchored some distance apart on either side of a shipping channel , linked by a chain . When a deep draft vessel passed through the trap it would pull the chain along with it , dragging the mines onto the sides of the ship ; the resulting double explosion often sank it . This system was not used extensively , but proved effective in blocking ports . Drifting contact mines . Drifting mines were occasionally used during World War I and World War II . However , they were more feared than effective . Sometimes floating mines break from their moorings and become drifting mines ; modern mines are designed to deactivate in this event . After several years at sea , the deactivation mechanism might not function as intended and the mines may remain live . Admiral Jellicoe ' s British fleet did not pursue and destroy the outnumbered German High Seas Fleet when it turned away at the Battle of Jutland because he thought they were leading him into a trap : he believed it possible that the Germans were either leaving floating mines in their wake , or were drawing him towards submarines , although neither of these was the case . Churchill promoted " Operation Royal Marine " in 1940 and again in 1944 where floating mines were put into the Rhine in France to float down the river , becoming active after a time calculated to be long enough to reach German territory . After World War I the drifting contact mine was banned , but was occasionally used during World War II . The drifting mines were much harder to remove than tethered mines after the war , and they caused about the same damage to both sides . Bottom contact mines . A bottom contact mine is the simplest form of mine . It is merely an explosive charge with some form of fuze fitted lying on the seafloor . They have been used against submarines , as submarines sometimes lie on the seafloor to reduce their acoustic signature . They are also used to prevent landing craft from reaching the shore and were a major obstacle during the D - Day landings . The Germans used antitank mines here with minor modifications to make them more reliable underwater , attaching the mines to the front of many of the obstacles seen in photos of the landing . These mines usually weighed 2 to 50 kg , including 1 to 40 kg of explosives ( TNT or hexatonal ) . Remotely controlled mines . Frequently used in combination with coastal artillery and hydrophones , controlled mines ( or command detonation mines ) can be in place in peacetime , which is a huge advantage in blocking important shipping routes . The mines can usually be turned into " normal " mines with a switch ( which prevents the enemy from simply capturing the controlling station and deactivating the mines ) , detonated on a signal or be allowed to detonate on their own . The earliest ones were developed around 1812 by Robert Fulton . The first remotely controlled mines were moored mines used in the American Civil War , detonated electrically from shore . They were considered superior to contact mines because they did not put friendly shipping at risk . Modern examples usually weigh 200 kg ( 440 lb ) , including 80 kg ( 175 lb ) of explosives ( TNT or hexatonal ) . Influence mines . These mines are triggered by the influence of a ship or submarine , rather than direct contact . Such mines incorporate electronic sensors designed to detect the presence of a vessel and detonate when it comes within the blast range of the warhead . The fuze s on such mines may incorporate one or more of the following sensors : magnetic , passive acoustic or water pressure displacement caused by the proximity of a vessel . First used during the First World War , their use became more general in the Second World War . The sophistication of influence mine fuze s has increased considerably over the years as first transistor s and then microprocessors have been incorporated into designs . Simple magnetic sensors have been superseded by total - field magnetometer s . Whereas early magnetic mine fuzes would respond only to changes in a single component of a target vessel ' s magnetic field , a total field magnetometer responds to changes in the magnitude of the total background field ( thus enabling it to better detect even degaussed ships ) . Similarly , the original broadband hydrophone s of 1940s acoustic mines ( which operate on the integrated volume of all frequencies ) have been replaced by narrow - band sensors which are much more sensitive and selective . Mines can now be programmed to listen for highly specific acoustic signature s ( e . g . a gas turbine powerplant and / or cavitation sounds from a particular design of propeller ) and ignore all others . The sophistication of modern electronic mine fuze s incorporating these Digital Signal Processing capabilities makes it much more difficult to detonate the mine with electronic countermeasures because several sensors working together ( e . g . magnetic , passive acoustic and water pressure ) allow it to ignore signals which are not recognised as being the unique signature of an intended target vessel . Modern influence mines such as the BAE Stonefish are computerised , with all the programmability that this implies e . g . the ability to quickly load new acoustic signature s into fuzes , or program them to detect a single , highly distinctive target signature . In this way , a mine with a passive acoustic fuze can be programmed to ignore all friendly vessels and small enemy vessels , only detonating when a very large enemy target passes over it . Alternatively , the mine can be programmed specifically to ignore all surface vessels regardless of size and exclusively target submarines . Even as far back as the Second World War it was possible to incorporate a " ship counter " facility into mine fuzes e . g . set the mine to ignore the first two ships to pass over it ( which could be mine - sweepers deliberately trying to trigger mines ) but detonate when the third ship passes overhead — which could be a high - value target such as an aircraft carrier or oil tanker . Even though modern mines are generally powered by a long life lithium battery , it is important to conserve power because they may need to remain active for months or even years . For this reason , most influence mines are designed to remain in a semi - dormant state until an unpowered ( e . g . deflection of a mu - metal needle ) or low - powered sensor detects the possible presence of a vessel , at which point the mine fuze powers up fully and the passive acoustic sensors will begin to operate for some minutes . It is possible to program computerised mines to delay activation for days or weeks after being laid ; similarly , they can be programmed to self - destruct or render themselves safe after a preset period of time , e . g . , 12 days or 12 months . Generally , the more sophisticated the mine design , the more likely it is to have some form of anti - handling device fitted in order to hinder clearance by divers or remotely piloted submersibles . Moored mines . The moored mine is the backbone of modern mine systems . They are deployed where water is too deep for bottom mines . They can use several kinds of instruments to detect an enemy , usually a combination of acoustic , magnetic and pressure sensor s , or more sophisticated optical shadows or electro potential sensors . These cost many times more than contact mines . Moored mines are effective against most kinds of ships . As they are cheaper than other anti - ship weapons they can be deployed in large numbers , making them useful area denial or " channelizing " weapons . Moored mines usually have lifetimes of more than 10 years , and some almost unlimited . These mines usually weigh 200 kg ( 440 lb ) , including 80 kg ( 175 lb ) of explosives ( hexatonal ) . In excess of 150 kg ( 330 lb ) of explosives the mine becomes inefficient , as it becomes too large to handle and the extra explosives add little to the mine ' s effectiveness . Bottom mines . Bottom mines are used when the water is no more than 60 meters ( 180 ft ) deep or when mining for submarines down to around 200 meters ( 660 ft ) . They are much harder to detect and sweep , and can carry a much larger warhead than a moored mine . Bottom mines commonly utilize multiple types of sensors , which are less sensitive to sweeping . These mines usually weigh between 150 and 1 , 500 kilograms ( 330 to 3 , 300 pounds ) , including between 125 and 1 , 400 kg ( 275 to 3 , 090 pounds ) of explosives . Unusual mines . Several specialized mines have been developed for other purposes than the common minefield . Bouquet mine . The bouquet mine is a single anchor attached to several floating mines . It is designed so that when one mine is swept / detonated , another takes its place . It is a very sensitive construction and lacks reliability . Anti sweep mine . The anti sweep mine is a very small mine ( 40 kg warhead ) with as small a floating device as possible . When the wire of a mine sweep hits the mine , it " sinks " , letting the sweep wire drag along the anchoring wire of the mine until the sweep hits the mine . That detonates the mine and cuts the sweeping wire . They are very cheap and usually used in combination with other mines in a minefield to make sweeping more difficult . One type is the Mark 23 used by the United States during World War II . Oscillating mine . The mine is hydrostatically controlled to maintain a pre - set depth below the water ' s surface independently of the rise and fall of the tide . Ascending mine . The ascending mine is a floating distance mine that may cut its mooring or in some other way float higher when it detects a target . It lets a single floating mine cover a much larger depth range . Homing mine . This is another name for the rocket mine or torpedo mine . Rocket mine . A Russian invention , the rocket mine is a bottom distance mine that fires a homing high - speed rocket ( not torpedo ) upwards towards the target . It is intended to allow a bottom mine to attack surface ships as well as submarines from a greater depth . One type is the Te - 1 rocket propelled mine . Torpedo mine . The torpedo mine is a self - propelled variety , able to lie in wait for a target and then pursue it e . g . the Mark 60 CAPTOR . Other designs such as the Mk 67 Submarine Launched Mobile Mine ( which is based on a Mark 37 torpedo ) are capable of swimming as far as 10 miles through or into a channel , harbor , shallow water area and other zones which would normally be inaccessible to craft laying the device . After reaching the target area they sink to the sea bed and act like conventionally laid influence mines . Generally , torpedo mines incorporate computerised acoustic and magnetic fuze s . The U . S . Mark 24 " mine " , code - named FIDO , was actually an ASW homing torpedo . The mine designation was disinformation to conceal its function . Mobile mine . The mine is propelled to its intended position by propulsion equipment such as a torpedo . After reaching its destination , it sinks to the seabed and operates like a standard mine . Nuclear mine . During the Cold War a test was conducted with naval mine fitted with tactical nuclear warheads for the " Baker " shot of Operation Crossroads . This weapon was experimental and never went into production . There have been some reports that North Korea may be developing a nuclear mine The Seabed Arms Control Treaty prevents the placement of nuclear weapons on the seabed beyond a 12 - mile coast zone . Daisy - chained mine . This comprises two moored , floating contact mines which are tethered together by a length of steel cable or chain . Typically , each mine is situated approximately away from its neighbour , and each floats a few metres below the surface of the ocean . When the target ship hits the steel cable , the mines on either side are drawn down the side of the ship ' s hull , exploding on contact . In this manner it is almost impossible for target ships to pass safely between two individually moored mines . Daisy - chained mines are a very simple concept which was used during World War II . Dummy mine . Plastic drums filled with sand or concrete are periodically rolled off the side of ships as real mines are laid in large mine - fields . These inexpensive false targets ( designed to be of a similar shape and size as genuine mines ) are intended to slow down the process of mine clearance : a mine - hunter is forced to investigate each suspicious sonar contact on the sea bed , whether it is real or not . Often a maker of Naval mines will provide both training and dummy versions of their mines . Mine laying . Historically several methods were used to lay mines . During the First and Second World Wars , the Germans used U - boat s to lay mines around the UK . In the Second World War , aircraft came into favour for mine laying with the one of largest such examples being the mining of the Japanese sea routes in Operation Starvation . Laying a minefield is a relatively fast process with specialized ships , which is still today the most common method . These minelayer s can carry several thousand mines and manoeuvre with high precision . The mines are dropped at a predefined interval into the water behind the ship . Each mine is recorded for later clearing , but it is not unusual for these recordings to be lost together with the ships . Therefore many countries demand that all mining operations shall be planned on land and records kept so the mines can later be recovered more easily . Other methods to lay minefields include : In some cases , mines are automatically activated upon contact with the water . In others , a safety lanyard is pulled ( e . g . one end attached to the rail of a ship , aircraft or torpedo tube ) which starts an automatic timer countdown before the arming process is complete . Typically , the automatic safety - arming process takes some minutes to complete . This is in order to give the people laying the mines sufficient time to move out of its activation / blast zone . Aerial mining in World War II . Germany . In the 1930s , Germany had experimented with the laying of mines by aircraft ; it became a crucial element in their overall mining strategy . Aircraft had the advantage of speed , and they would never get caught in their own minefields . German mines held a large 1 , 000 lb . ( 450 kg ) explosive charge . From April to June 1940 , the Luftwaffe laid 1 , 000 mines in British waters . Soviet ports were mined , as was the Arctic convoy route to Murmansk . The Heinkel He 115 could carry two medium or one large mine while the Heinkel He 59 , Dornier Do 18 , Junkers Ju 88 and Heinkel He 111 could carry more . Soviet Union . The USSR was relatively ineffective in its use of naval mines in WWII in comparison with its record in previous wars . Small mines were developed for use in rivers and lakes , and special mines for shallow water . A very large chemical mine was designed to sink through ice with the aid of a melting compound . Special aerial mine designs finally arrived in 1943 – 1944 , the AMD - 500 and AMD - 1000 . Various Soviet Naval Aviation torpedo bombers were pressed into the role of aerial mining in the Baltic Sea and the Black Sea , including Ilyushin DB - 3 s , Il - 4 s and Lend Lease Douglas Boston III s . United Kingdom . In September 1939 , the UK announced the placement of extensive defensive minefields in waters surrounding the Home Islands . Offensive aerial mining operations began in April 1940 when 38 mines were laid at each of these locations : the Elbe River , the port of Lübeck and the German naval base at Kiel . In the next 20 months , mines delivered by aircraft sank or damaged 164 Axis ships with the loss of 94 aircraft . By comparison , direct aerial attacks on Axis shipping had sunk or damaged 105 vessels at a cost of 373 aircraft lost . The advantage of aerial mining became clear , and the United Kingdom geared up for it . A total of 48 , 000 aerial mines were laid by the Royal Air Force ( RAF ) in the European Theatre during World War II . United States . The United States ' s early aerial mining efforts used smaller aircraft unable to carry many mines . Using TBF Avenger torpedo bombers , the US Navy mounted a direct aerial mining attack on enemy shipping in Palau on 30 March 1944 in concert with simultaneous conventional bombing and strafing attacks . The dropping of 78 mines stopped 32 Japanese ships from escaping Koror harbor ; the combined operation sank or damaged 36 ships . Two Avengers were lost ; their crews were recovered . The mines brought port usage to a halt for 20 days ; further mine - laying in the area contributed to the Japanese abandoning Palau as a base . As early as 1942 , American mining experts such as Naval Ordnance Laboratory scientist Dr . Ellis A . Johnson , Commander , Naval Reserve , suggested massive aerial mining operations against Japan ' s " outer zone " ( Korea and northern China ) as well as the " inner zone " , their home islands . First , aerial mines would have to be developed further and manufactured in large numbers . Second , laying the mines would require a sizable air group . The US Army Air Force had the carrying capacity but considered mining to be the Navy ' s job . The US Navy lacked suitable aircraft . Johnson set about convincing General Curtis LeMay of the efficacy of very heavy bombers laying aerial mines . In the meantime , B - 24 Liberator , PBY Catalina and other available bomber aircraft took part in localized mining operations in the Southwest Pacific and the China Burma India ( CBI ) Theaters , beginning with a very successful attack on the Yangon River in February 1943 . Aerial minelaying operations involved a coalition of British , Australian and American aircrews , with the RAF and the Royal Australian Air Force ( RAAF ) carrying out 60 % of the sorties and the USAAF and US Navy covering 40 % . Both British and American mines were used . Japanese merchant shipping suffered tremendous losses , while Japanese mine sweeping forces were spread too thin attending to far - flung ports and extensive coastlines . Admiral Thomas C . Kinkaid , who directed nearly all RAAF mining operations in CBI , heartily endorsed aerial mining , writing in July 1944 that " aerial mining operations were of the order of 100 times as destructive to the enemy as an equal number of bombing missions against land targets . " Finally , in March 1945 , Operation Starvation began in earnest , using 160 of LeMay ' s B - 29 Superfortress bombers to attack Japan ' s inner zone . Almost half of the mines were the US - built Mark 25 model , carrying 1250 lbs of explosives and weighing about 2 , 000 lbs . Other mines used included the smaller 1 , 000 lb Mark 26 . 15 B - 29s were lost while 293 enemy merchant ships were sunk or damaged . 12 , 000 aerial mines were laid , a significant barrier to Japan ' s access to outside resources . Prince Fumimaro Konoe said after the war that the aerial mining by B - 29s had been " equally as effective as the B - 29 attacks on Japanese industry at the closing stages of the war when all food supplies and critical material were prevented from reaching the Japanese home islands . " The United States Strategic Bombing Survey ( Pacific War ) concluded that it would have been more efficient to combine the United States ' s effective anti - shipping submarine effort with land - and carrier - based air power to strike harder against merchant shipping and begin a more extensive aerial mining campaign earlier in the war . Survey analysts projected that this would have starved Japan , forcing an earlier end to the war . After the war , Dr . Johnson looked at the Japan inner zone shipping results , comparing the total economic cost of submarine - delivered mines versus air - dropped mines and found that , though 1 in 12 submarine mines connected with the enemy as opposed to 1 in 21 for aircraft mines , the aerial mining operation was about ten times less expensive per enemy ton sunk . Clearing WWII aerial mines . Between 600 , 000 and 1 , 000 , 000 naval mines of all types were laid in World War II . Advancing military forces worked to clear mines from newly taken areas , but extensive minefields remained in place after the war . Air - dropped mines had an additional problem for mine sweeping operations : they were not meticulously charted . In Japan , much of the B - 29 mine - laying work had been performed at high altitude , with the drifting on the wind of mines carried by parachute adding a randomizing factor to their placement . Generalized danger areas were identified , with only the quantity of mines given in detail . Mines used in Operation Starvation were supposed to be self - sterilizing , but the circuit did not always work . Clearing the mines from Japanese waters took so many years that the task was eventually given to the Japan Maritime Self - Defense Force . For the purpose of clearing all types of naval mines , the Royal Navy employed German crews and minesweepers from June 1945 to January 1948 , organised in the German Mine Sweeping Administration , the " GMSA " , which consisted of 27 , 000 members of the former " Kriegsmarine " and 300 vessels . Mine clearing wasn ' t always successful : a number of ships were damaged or sunk by mines after the war . Two such examples were the Liberty ship s " Pierre Gibault " which was scrapped after hitting a mine in a previously cleared area off the Greek island of Kythira in June 1945 , and " Nathaniel Bacon " which hit a minefield off Civitavecchia , Italy in December 1945 , caught fire , was beached , and broke in two . Damage . The damage that may be caused by a mine depends on the " shock factor value " , a combination of the initial strength of the explosion and of the distance between the target and the detonation . When taken in reference to ship hull plating , the term " Hull Shock Factor " ( HSF ) is used , while keel damage is termed " Keel Shock Factor " ( KSF ) . If the explosion is directly underneath the keel , then HSF is equal to KSF , but explosions that are not directly underneath the ship will have a lower value of KSF . Direct damage . Usually only created by contact mines , direct damage is a hole blown in the ship . Among the crew , fragmentation wounds are the most common form of damage . Flooding typically occurs in one or two main watertight compartments which can sink smaller ships or disable larger ones . Contact mine damage often occurs at or close to the waterline near the bow , but depending on circumstances a ship could be hit anywhere on its outer hull surface ( the USS Samuel B Roberts mine attack being a good example of a contact mine detonating amidships and underneath the ship ) . Bubble jet effect . The bubble jet effect occurs when a mine detonates in the water a short distance away from the ship . The explosion creates a bubble in the water , and due to the difference in pressure , the bubble will collapse from the bottom . The bubble is buoyant and so it rises towards the surface . If the bubble reaches the surface as it collapses it can create a pillar of water that can go over a hundred meters into the air ( a " columnar plume " ) . If conditions are right and the bubble collapses onto the ship ' s hull the damage to the ship can be extremely serious ; the collapsing bubble forms a high energy jet that can break a meter wide hole straight through the ship , flooding one or more compartments , and is capable of breaking smaller ships apart . The crew in the areas hit by the pillar are usually killed instantly . Other damage is usually limited . The Baengnyeong incident , in which the ROKS " Cheonan " broke in half and sank off the coast South Korea in 2010 , is thought by some to have been caused by the bubble jet effect . Shock effect . If the mine detonates at a distance from the ship , the change in water pressure causes the ship to resonate . This is frequently the most deadly type of explosion , if it is strong enough . The whole ship is dangerously shaken and everything onboard is tossed around . Engines rip from their beds , cables from their holders , etc . A badly shaken ship usually sinks quickly , with hundreds , or even thousands of small leaks all over the ship and no way to power the pumps . The crew fare no better , as the violent shaking tosses them around . This shaking is powerful enough to cause disabling injury to knees and other joints in the body , particularly if the affected person stands on surfaces connected directly to the hull ( such as steel decks ) . The resulting gas cavitation and shock - front - differential over the width of the human body is sufficient to stun or kill divers . Countermeasures . Weapons are frequently a few steps ahead of countermeasures , and mines are no exception . In this field the British , with their large seagoing navy , have had the bulk of world experience , and most anti - mine developments , such as de - gaussing and the double - L sweep were British inventions . When on operational missions , such as the recent invasion of Iraq , the US still relies on British and Canadian minesweeping services . The US has worked on some innovative mine hunting countermeasures , such as the use of military dolphin s to detect and flag mines . However , they are of questionable effectiveness . Passive countermeasures . Ships can be designed to be difficult for mines to detect , to avoid detonating them . This is especially true for minesweepers and mine hunters that work in minefields , where a minimal signature outweighs the need for armour and speed . These ships have hulls of glass fibre or wood instead of steel to avoid magnetic signatures , they use special propulsion systems , such as Voith - Schneider propellers , to limit the acoustic signature . They are built with hulls that produce a minimal pressure signature . These measures create other problems . They are expensive , slow , and vulnerable to enemy fire . Therefore , they need protection . Many modern ships have a mine - warning sonar — a simple sonar looking forward and warning the crew if it detects possible mines ahead . It is only effective when the ship is moving slowly . < br > A steel - hulled ship can be " degaussed " ( more correctly , de - oerstedted or depermed ) using a special degaussing station that contains many large coils and induces a magnetic field in the hull with alternating current to demagnetize the hull . This is a rather problematic solution , as magnetic compasses need recalibration and all metal objects must be kept in exactly the same place . Ships slowly regain their magnetic field as they travel through the Earth ' s magnetic field , so the process has to be repeated every six months . A simpler variation of this technique , called " wiping " , was developed by Charles F . Goodeve which saved time and resources . Between 1941 and 1943 the US Naval Gun factory ( a division of the Naval Ordnance Laboratory ) in Washington D . C . built physical models of all US Naval ships . Three kinds of steel were used in shipbuilding : mild steel for bulkheads , a mixture of mild steel and high tensile steel for the hull , and special treatment steel for armor plate . The models were placed within coils which could simulate the Earth ' s magnetic field at any location . The magnetic signatures were measured with degaussing coils . The objective was to reduce the vertical component of the combination of the Earth ' s field and the ship ' s field at the usual depth of German mines . From the measurements , coils were placed and coil currents determined to minimize the chance of detonation for any ship at any heading at any latitude . Some ships are built with magnetic inductor s , large coils placed along the ship to counter the ship ' s magnetic field . Using magnetic probes in strategic parts of the ship , the strength of the current in the coils can be adjusted to minimize the total magnetic field . This is a heavy and clumsy solution , suited only to small - to - medium sized ships . Boats typically lack the generators and space for the solution , while the amount of power needed to overcome the magnetic field of a large ship is impractical . Active countermeasures . Active countermeasures are ways to clear a path through a minefield or remove it completely . This is one of the most important tasks of any mine warfare flotilla . Mine sweeping . A sweep is either a contact sweep , a wire dragged through the water by one or two ships to cut the mooring wire of floating mines , or a distance sweep that mimics a ship to detonate the mines . The sweeps are dragged by minesweeper s , either purpose - built military ships or converted trawlers . Each run covers between one and two hundred meters , and the ships must move slowly in a straight line , making them vulnerable to enemy fire . This was exploited by the Turkish army in the Battle of Gallipoli in 1915 , when mobile howitzer batteries prevented the British and French from clearing a way through minefields . If a contact sweep hits a mine , the wire of the sweep rubs against the mooring wire until it is cut . Sometimes " cutters " , explosive devices to cut the mine ' s wire , are used to lessen the strain on the sweeping wire . Mines cut free are recorded and collected for research or shot with a deck gun . Minesweepers protect themselves with an oropesa or paravane instead of a second minesweeper . These are torpedo - shaped towed bodies , similar in shape to a Harvey Torpedo , that are streamed from the sweeping vessel thus keeping the sweep at a determined depth and position . Some large warships were routinely equipped with paravane sweeps near the bows in case they inadvertently sailed into minefields — the mine would be deflected towards the paravane by the wire instead of towards the ship by its wake . More recently , heavy - lift helicopters have dragged minesweeping sleds , as in the 1991 Persian Gulf War . The distance sweep mimics the sound and magnetism of a ship and is pulled behind the sweeper . It has floating coils and large underwater " drums " . It is the only sweep effective against bottom mines . During the Second World War , RAF Coastal Command used Vickers Wellington bombers Wellington DW . Mk I fitted with degaussing coils to trigger magnetic mines . Modern influence mines are designed to discriminate against false inputs and are therefore much harder to sweep . They often contain inherent anti - sweeping mechanisms . For example , they may be programmed to respond to the unique noise of a particular ship - type , its associated magnetic signature and the typical pressure displacement of such a vessel . As a result , a mine - sweeper must accurately guess and mimic the required target signature in order to trigger detonation . The task is complicated by the fact that an influence mine may have one or more of a hundred different potential target signatures programmed into it . Another anti - sweeping mechanism is a ship - counter in the mine fuze . When enabled , this allows detonation only after the mine fuze has been triggered a pre - set number of times . To further complicate matters , influence mines may be programmed to arm themselves ( or disarm automatically — known as " self - sterilization " ) after a pre - set time . During the pre - set arming delay ( which could last days or even weeks ) the mine would remain dormant and ignore any target stimulus , whether genuine or faked . When influence mines are laid in an ocean minefield , they may have various combinations of fuze settings configured . For example , some mines ( with the acoustic sensor enabled ) may become active within three hours of being laid , others ( with the acoustic and magnetic sensors enabled ) may become active after two weeks but have the ship - counter mechanism set to ignore the first two trigger events , and still others in the same minefield ( with the magnetic and pressure sensors enabled ) may not become armed until three weeks have passed . Groups of mines within this mine - field may have different target signatures which may or may not overlap . The fuzes on influence mines allow many different permutations , which complicates the clearance process . Mines with ship - counters , arming delays and highly specific target signatures in mine fuzes can falsely convince a belligerent that a particular area is clear of mines or has been swept effectively because a succession of vessels have already passed through safely . Mine hunting . Mine hunting is very different from sweeping , although some minehunter s can do both tasks . Mines are hunted using sonar , then inspected and destroyed either by divers or ROV s ( remote controlled unmanned mini submarines ) . It is slow , but also the most reliable way to remove mines . Mine hunting started during the Second World War , but it was only after the war that it became truly effective . Sea mammals ( mainly the Bottlenose Dolphin ) have been trained to hunt and mark mines , most famously by the U . S . Navy Marine Mammal Program . Mine - clearance dolphins were deployed in the Persian Gulf during the Iraq War in 2003 . The Navy claims that these dolphins were effective in helping to clear more than 100 antiship mines and underwater booby trap s from Umm Qasr Port . French naval officer Jacques Yves Cousteau ' s Undersea Research Group was once involved in mine - hunting operations : They removed or detonated a variety of German mines , but one particularly defusion - resistant batch — equipped with acutely sensitive pressure , magnetic , and acoustic sensors and wired together so that one explosion would trigger the rest — was simply left undisturbed for years until corrosion would ( hopefully ) disable the mines . Mine breaking . A more drastic method is simply to load a cargo ship with cargo that makes her less vulnerable to sinking ( wood for example ) and drive her through the minefield , letting the ship to be protected follow the same path . This method was employed by the German Kriegsmarine during WWII , using converted ships known as " Sperrbrecher " ( " barrage breaker " ) . Alternatively , a shallow draught vessel can be steamed through the minefield at high speed to generate a pressure wave sufficient to trigger mines , with the minesweeper moving fast enough to be sufficiently clear of the pressure wave so that triggered mines do not destroy the ship itself . These techniques are the only way to sweep pressure mines . The technique can be simply countered by use of a ship - counter , set to allow a certain number of passes before the mine is actually triggered . Modern doctrine calls for ground mines to be hunted rather than swept . A new system is being introduced for sweeping pressure mines however counters are going to remain a problem . An updated form of mine breaking is the use of small unmanned ROV s that simulate the acoustic and magnetic signatures of larger ships and are built to survive exploding mines . Repeated sweeps would be required in case one or more of the mines had its " ship counter " facility enabled i . e . were programmed to ignore the first 2 , 3 , or even 6 target activations . National arsenals . US mines . The United States Navy MK56 ASW mine ( the oldest still in use by the US ) was developed in 1966 . More advanced mines include the MK60 CAPTOR ( short for " encapsulated torpedo " ) , the MK62 and MK63 Quickstrike and the MK67 SLMM ( Submarine Launched Mobile Mine ) . Today , most U . S . naval mines are delivered by aircraft . MK67 SLMM Submarine Launched Mobile Mine < br > The SLMM was developed by the United States as a submarine deployed mine for use in areas inaccessible for other mine deployment techniques or for covert mining of hostile environments . The SLMM is a shallow - water mine and is basically a modified Mark 37 torpedo . General characteristics MK65 Quickstrike < br > The Quickstrike is a family of shallow - water aircraft - laid mines used by the United States , primarily against surface craft . The MK65 is a 2 , 000 - lb ( 900 kg ) dedicated , purpose - built mine . However , other Quickstrike versions ( MK62 , MK63 , and MK64 ) are converted general - purpose bombs . These latter three mines are actually a single type of electronic fuze fitted to Mk82 , Mk83 and Mk84 air - dropped bombs . Because this latter type of Quickstrike fuze only takes up a small amount of storage space compared to a dedicated sea mine , the air - dropped bomb casings have dual purpose i . e . can be fitted with conventional contact fuzes and dropped on land targets , or have a Quickstrike fuze fitted which converts them into sea mines . General characteristics MK56 < br > General characteristics Royal Navy . According to a statement made to the UK Parliament in 2002 : However , a British company ( BAE Systems ) does manufacture the Stonefish influence mine for export to friendly countries such as Australia , which has both war stock and training versions of Stonefish , in addition to stocks of smaller Italian MN103 Manta mines . The computerised fuze on a Stonefish mine contains acoustic , magnetic and water pressure displacement target detection sensors . Stonefish can be deployed by fixed - wing aircraft , helicopters , surface vessels and submarines . An optional kit is available to allow Stonefish to be air - dropped , comprising an aerodynamic tail - fin section and parachute pack to retard the weapon ' s descent . The operating depth of Stonefish ranges between 30 and 200 metres . The mine weighs 990 kilograms and contains a 600 kilogram aluminised PBX explosive warhead .