West Loch disaster The West Loch Disaster was an American maritime accident during World War II at the Pearl Harbor U . S . Naval Base in Hawaii . The incident , which occurred just after 3pm on Sunday 21 May 1944 , began following an explosion in a staging area for Landing Ships , Tank ( LSTs ) and other amphibious assault ship s in West Loch . A fire quickly spread among the ships being prepared for Operation Forager , the invasion of the Japanese - held Mariana Islands . Over the next 24 hours , six LSTs sank , 163 naval personnel died and 396 were injured . A subsequent Naval Board of Inquiry never determined the exact cause of the disaster . But it concluded the initial explosion was caused when a mortar round aboard detonated during an unloading operation because it was either dropped or went off when gasoline vapors ignited . The incident – together with the Port Chicago disaster two months later – led to major changes in weapon handling practices within the United States Navy . The LST wreckage was quickly cleared in a salvage operation and dumped at sea south of Hawaii . Only the hull of the partially beached was left in West Loch . A press blackout was enforced and naval personnel were ordered not to talk about the incident . The disaster is therefore not as well known as the Japanese Attack on Pearl Harbor of December 1941 ; in part because it was classified top secret until 1960 . During the salvage and removal of the wrecks from West Loch , the U . S . Navy found remains of a Japanese midget submarine . Researchers now believe this to be the fifth Japanese midget submarine used in the attack in December 1941 . Background . In May 1944 , the West Loch area of Pearl Harbor was unusually crowded with various vessels as it was being used as a staging area for the upcoming Operation Forager . Twenty - nine Landing Ships , Tank ( LSTs ) were tied up , beam to beam , at six Tare piers . Many of the LSTs , in addition to carrying their own complement of munitions and fuel , were also fully loaded with the munitions , fuel , vehicles , equipment , and other general stores required by the 2nd and 4th Marine Division s for the invasion of the Marianas , that was to begin in mid - June . To aid quick deployment once ashore , high - octane gasoline was stored in barrels on deck . In the weeks leading up to the incident , the vessels and crews had all been training for the upcoming invasion . The LSTs were each crewed by around 120 Navy sailors or Coast Guardsmen , and manned by around 200 Marine loaders , drivers and mechanics . The rapid expansion of the fleet meant many of the crews were made up of inexperienced sailors and Marines . On 21 May , many of the LSTs had only half their crew aboard because , after a week of intensive training , most officers and ratings had been given shore leave . Explosion . At 15 : 08 , the moored at Tare 8 exploded sending a large fireball into the sky . The noise was heard miles away at Pearl Harbor Headquarters . More explosions of increasing intensity followed , sparking fears of a Japanese attack or even an earthquake . Fire and debris raining down on the fuel and munitions stored on the decks of other LSTs had caused an explosive chain reaction . Within minutes , 200 men had been blown into the water . Eleven wooden buildings on the shore were destroyed and vehicles blown on their side . In all , 20 buildings were damaged . Initial efforts by the crews to fight the fires were impeded by the heat , although some ships further away managed to muster damage control parties . Many of the LSTs tied together at Tare 8 began to sink . Within the hour , Admiral Richmond K . Turner was directing fire - fighting efforts from a launch . Various LSTs managed to move to safety under their own power or with assistance by tugboats . However others were abandoned and allowed to drift , spreading fires , before sinking in the channel . Leaking oil ignited on the water also spread fires to Tares 7 and 9 even though they had been unharmed after the first explosions at Tare 8 . Eventually tugboats and foam - carrying salvage ships from Pearl Harbor arrived to fight the spreading fires . One ship managed to turn a drifting LST away from a collision course with an ammunition ship docked across the loch at the ammunition depot . A final explosion occurred at 22 : 30 ; while several LSTs continued to burn for 24 hours . In total , the harbor tugs , , and , the net tender , the chartered tug " Mikioi " , and smaller tugs " YTL - 233 " , " YTL - 306 " , " YTL - 307 " , " YTL - 308 " , " YTL - 309 " , and " YTL - 339 " were damaged while engaged in fire control efforts . Casualties . The initial official account listed 27 dead and 100 missing . The majority of sources state the final death toll as 163 men , with a further 396 wounded . However in 2005 the magazine , " Sea Classics " , claimed the total dead was 392 , of which 163 were sailors . The other 229 were Marines from the newly formed 2nd and 4th Marine Division s , while Army dead were not recorded in the confusion . Pearl Harbor attack survivor and historical researcher , Ray Emory , also disputes the official death toll ; he believes 132 men died at West Loch . Investigation . A Naval Board of Inquiry , under Rear Admiral John F . Shafroth Jr . , was opened in Pearl Harbor the following day . An early theory that the incident was the result of a Japanese submarine attack was dismissed as impractical because of the depth of the West Loch and the presence of anti - submarine nets . The executive officer of " LST - 353 " stated that immediately prior to the explosion , Army stevedores were unloading mortar ammunition from a Landing craft tank ( LCT ) on the deck of his ship . The procedure to remove the mortar rounds was being undertaken because training had proved M2 mortar s could not be fired accurately from LCTs . The enquiry was told the unit given the task to unload the mortar rounds had received no training for the task . Meanwhile 80 drums of fuel were stacked just from the elevator being used to unload the LCT . Following testimony , the Naval Enquiry Board concluded that a mortar round exploded on " LST - 353 " sparking a chain reaction . However it could not determine the actual cause of the detonation because all those nearest to the explosion were killed . This conclusion was sustained by subsequent reviews . The two most plausible explanations were considered to be : The enquiry also heard the conduct of the inexperienced crews may have exacerbated the disaster . Lieutenant Commander Joseph B . Hoyt , USNR , the Commander of LST Group 39 , Flotilla 13 , criticized many of the LST crews for abandoning their vessels too early , leaving them to sink or drift , rather than fire - fighting or attempting to beach them . However he praised the efforts of crew from the " LST - 274 " which was badly damaged but saved . Several crews and skippers were called to account for inadequate reactions to the emergency , although the severity of the conditions were cited as mitigating factors . In the end no courts - martial or letters of reprimand were issued to anyone involved . The practice of loading fuel and munitions aboard closely moored vessels was deemed to be necessary under the conditions of war and the layout of Pearl Harbor U . S . Navy Base . A recommendation by the Board to avoid nesting in future was criticized by Admiral Chester W . Nimitz as impractical . Reporting . The United States military ordered a press blackout following the incident . The official inquiry was marked Top Secret and survivors and eyewitnesses were not permitted to mention the incident in letters home . Four days after the incident , the authorities released a one - paragraph statement noting an explosion had caused " some loss of life , a number of injuries and resulted in the destruction of several small vessels " . It was only after Operation Forager that a fuller account was released to the press . The entire incident was not declassified and made public until 1960 . As a result of the secrecy surrounding the incident , it has been asserted that the public knows little about Pearl Harbor ' s " second disaster " . As of 1997 , the only book about the incident , " The West Loch Story " , was privately published by survivor , William L . C . Johnson . He alleges that a full account had not emerged from the Navy until 1964 , and that the incident had been caused by careless smoking . Impact on Operation Forager . Six LSTs were sunk ( " LST - 39 " , " LST - 43 " , " LST - 69 " , LST - 179 , LST - 353 , and " LST - 480 " ) , two already carrying smaller , fully loaded Landing craft tank s ( " LCT - 961 " , 963 and 983 ) lashed to their decks . Several LSTs were damaged and / or ran aground . Four ( including LST - 205 and LST - 225 ) could not be repaired in time for the invasion . Seventeen tracked landing vehicles ( LVT ) and eight guns were destroyed . Other sources place the total number of destroyed LSTs at nine . With reinforcement of the fleet from elsewhere , and through quick repair efforts , Operation Forager was only delayed by one day as a result of the incident , with the operation commencing essentially as planned three weeks later . Memorials . In the weeks following the disaster , all wreckage was salvaged and removed , with the exception of ( sometimes reported as " LST - 353 " ) . Its bow can be seen at , rusting , the craft having been beached during the disaster . In April 1995 , the first memorial to the disaster was unveiled : a table - sized plaque sited on the shore of the loch . At the behest of Congress , gravestones of unidentified victims in the National Memorial Cemetery of the Pacific were amended in the 2000s ( decade ) from recording simply " unknown " , to " Unknown , West Loch Disaster , May 21 , 1944 " . The Navy commemorated the 65th anniversary of the disaster on 21 May 2009 . Legacy . As a result of the incident , and the Port Chicago disaster two months later , the Navy drastically changed its ordnance - handling procedures . It insisted on full training for handlers , munitions to be redesigned for safer handling , and that vessels should no longer be nested together when ammunition was being loaded or handled . It is also possible that the salvage operation undertaken to clear the loch after the disaster inadvertently lengthened the hunt for the " fifth midget submarine " involved in the 1941 attack on Pearl Harbor . After three pieces of a midget submarine were discovered three miles south of Pearl Harbor , a working theory was developed that this was the only submarine in a group of five Japanese Ko - hyoteki class submarine s involved in the attack that had not yet been accounted for . Researchers posited that it had penetrated the harbor to attack Battleship Row , before escaping into West Loch and being scuttled by the two - man crew . Lying on the bed of the loch , it was then salvaged along with the remains of the LSTs , LCTs and landing tanks , and then dumped at sea .