Bonus dungeon Bonus dungeon , also known as secret dungeon or optional dungeon , is an optional location that is usually much more difficult than the main game with enemies that are much higher level than on other parts of the game . These dungeons are considered sidequest s and often contain the most powerful equipment and , sometimes , summons that can only be obtained by completing the dungeon . The boss fought at the end of a bonus dungeon is often a superboss . A game can have multiple bonus dungeons . Bonus dungeons are common features added to remakes of older games , to give experienced players new material to test their skills against , and to make the remake more lucrative purchase for people who have already completed an earlier version of the game . Appearances . " Final Fantasy " . Soul of Chaos . As the original " Final Fantasy " is the most remade game in the series , it has had plenty of new content added over the years . Soul of Chaos is the collective name of the four bonus dungeons originating in the " " version that reappear in the " 20th Anniversary Edition " and iOS versions . The Android version doesn ' t have any bonus dungeon . Each dungeon is tied to one of the four worldly elements and are initially sealed by a statue of their element ' s respective Chaos Fiend . Each dungeon , with the exception of Earthgift Shrine , is significantly longer than any in the main game . Major boss es from future games in the series are fought in the shrines , and the dungeons include many new and powerful pieces of equipment , as well as enemies that were not in the original game . Labyrinth of Time . The Labyrinth of Time is the new bonus dungeon in the " Final Fantasy 20th Anniversary " and iOS versions of the original " Final Fantasy " . It consists of various floors , each one containing puzzles that must be solved on time for the player to proceed . At the deepest floor players will face Chronodia , Master of Time , the new superboss . " Final Fantasy II " . Soul of Rebirth . The Soul of Rebirth is a bonus quest in the " Dawn of Souls " , " 20th Anniversary " , and iOS versions of " Final Fantasy II " . It becomes available after completing the game , after which the player can select " Soul of Rebirth " from the menu . Soul of Rebirth gives the player a party consisting of three party members they had in the past , with the addition of Scott , who join with whatever spells , equipment and stats they had when they left the party . Each of the characters ' ultimate weapons can be found in the dungeon , and at the end of the quest , the player faces the light half of the Emperor . " Final Fantasy III " . There are numerous optional areas that provide the party with valuable items , including weapons , armor , and spells . Sunken Cave . Located underwater the small island to the extreme southeast of the Surface World , the party will need to dive with the " Nautilus " . The Sunken Cave has a wealth of chests containing lots of equipment and a few items . Saronia Catacombs . This optional area is accessible from underwater in the southeast part of Saronia . The party can fight Odin here obtain the Summon spell Catastro , and steal the Gungnir from him , as well pick up some equipment and items from chests . Lake Dohr . Lake Dohr is to the west of Castle Argus over a small mountain range , requiring the " Invincible " to reach . The party can fight Leviathan here to obtain the summon spell Leviath . The treasure chests here contain a wealth of attack items , as well as some equipment . Bahamut ' s Lair . The cave itself is located to the southeast of Vikings ' Cove , but the player must cross the mountains to the east of Bahamut ' s Lair on the " Invincible " to reach the entrance . The party can fight Bahamut here to obtain him as a summon . Eureka . Eureka contains some of the best equipment in the game . A gateway to it can be found at the bottom floor of the Crystal Tower , but the Eureka Key is required . Doga and Unei unlock the Eureka Key , and give it to the Warriors of Light , granting them access to Eureka , knowing they need better equipment to fight Xande . ? ? ? is an unnamed , secret underwater dungeon present in the 3D remakes . To unlock the dungeon , the player must finish the Mognet sidequest and retrieve every single letter . Located in the cave is Red Dragon , Green Dragon and Yellow Dragon , which have Onion equipment as their common and rare drops , and a secret superboss , the Iron Giant . " Final Fantasy IV " . Lair of the Father . Lair of the Father is an optional dungeon in all versions of " Final Fantasy IV " , where the player can acquire the Eidolon Bahamut . The player can visit the cave as soon as they acquire the " Lunar Whale " and fly to the Red Moon . Cave of Trials . The Cave of Trials is a bonus dungeon appearing in the " Advance " and " " releases . The dungeon has eight floors and the final floor contains five weapons guarded by bosses , one for each of the five party members players can swap out . The weapon can only be acquired if the correct member to wield it is in the party . Each of these weapons correspond to the characters who become available after the Giant of Babil to put them on - par with the rest of the group , who can acquire their ultimate weapons in the Lunar Subterrane . However , still stronger weapons can be acquired in the Lunar Ruins . Lunar Ruins . Lunar Ruins is a bonus dungeon in " Final Fantasy IV Advance " and " Complete Collection " , unlocked by completing the game . The floors are randomized with ten sets of floors of which the sequence of the sets of floor is fixed . In each set , there are five normal floors and a a sixth gate floor , which contains a save point and a door to each playable character ' s challenge , except for the tenth set , which leads to Zeromus EG , a new superboss . The mobile phone version of " Final Fantasy IV " has an all new " EX Dungeon " , which is a remake of the Lunar Ruins . Challenge Dungeon . Every character with their own tale has a Challenge Dungeon . They become available to explore by talking to Challengingway after the tale has been cleared . The Challenge Dungeons are difficult multi - floor dungeons with powerful enemies and often bosses , but for completing them the player receives a rare item or equipment piece . Challenge Dungeons must be completed multiple times to win all the items they offer . These dungeons are not available in the 3D versions . " Final Fantasy V " . Gil Cave . Gil Cave exists only in the second world connecting the Kingdom of Bal to the mainland entrance of the Big Bridge . By following a hidden path in the south of the cave , one can find the Gil Turtle Path . It houses a great treasure of gil , as well as dangerous and extremely powerful Gil Turtles , which are usually encountered every third step . The path may be completed multiple times for more gil . Phoenix Tower . The Phoenix Tower is a thirty floor tower found in the merged world . There are two doors in every floor : one will unfold the stairwell to the next floor , while the other is guarded by a random monster . Every five floors there will be pots on the right and left sides and one will contain an amount of GP equal to the floor number multiplied by 1000 , and the other is revealed to be a Magic Pot . All other encounters apart from the Magic Pots are inescapable and the enemies tend to hit the party with strong status ailments . Completing the tower awards the Phoenix summon . Sealed Temple . The Sealed Temple is a secret dungeon in " Final Fantasy V Advance " . It is located underwater , south of Phantom Village , and contains four crystal shards with the jobs of Cannoneer , Gladiator , Oracle , and Necromancer , although the last lies at the end of the Cloister of the Dead . In the temple the players can find the strongest enemies and bosses of the game , including Omega Mk . II and Neo Shinryu . " Final Fantasy VI " . In the World of Ruin visiting any areas after obtaining the airship is optional , but doing the areas lets the player recruit new and old party members and obtain espers . Many players consider the recruiting of all playable cast before the final battle as canon , and therefore most areas in the World of Ruin are not really considered sidequests or bonus dungeons . Cultists ' Tower . The Cultists ' Tower was built and is inhabited by the Cult of Kefka , a group that worships Kefka Palazzo . The tower is the tallest structure in the game with dozens of floors over four screens of staircases . All offensive commands , except Magic , are sealed , and unless Umaro is brought along , the party is limited to the use of spells and items in battle . At the top lies the unique relic Soul of Thamasa , but taking it causes leader of the cult , the Magic Master , to attack the player . There are no save points in the tower , and the Holy Dragon , one of the eight legendary dragons , resides in one of the tower ' s treasure rooms . Ebot ' s Rock . Ebot ' s Rock is located north of the town of Thamasa in the World of Ruin . Hidon , a beast that was hunted by Strago and Gungho in their youth , lives there . The cave is dark , and the player only has a small circular area of sight . The player must travel throughout Ebot ' s Rock , collecting enough Coral from treasure chests that a talking treasure chest will move allowing access to Hidon ' s chamber . The player can learn Strago ' s most powerful Lore from it . Dragons ' Den . The Dragons ' Den is a bonus dungeon in " Final Fantasy VI Advance " and subsequent ports located north of the Dragon ' s Neck Coliseum on an island with a single tree . Access is given once the player has defeated the eight legendary dragons . The player can obtain the most powerful equipment pieces in the game in the den , guarded by the most powerful bosses . " Final Fantasy VII " . Ancient Forest . Ancient Forest is located in the Cosmo Area accessed with a green , black or gold chocobo , or by defeating Ultimate Weapon first . In the forest the player must solve some puzzles to find rare Materia and weapons . Gelnika . The sunken Gelnika is a crashed airplane that lies on the Bottom of the Sea to the south of Costa del Sol . The plane can be accessed after the player has acquired the submarine . Even after sinking to the ocean floor , the plane ' s interior keeps from flooding , allowing for one to enter the sunken aircraft from the ocean . Gelnika holds some of the game ' s most difficult random encounter s , and also some of its best treasures . " Final Fantasy VIII " . Tomb of the Unknown King . The Tomb of the Unknown King is a location near Deling City , and by doing the sidequest inside the player can obtain the Guardian Force Brothers . Most of the areas are tunnels , making the tomb appear straightforward , but if the player backtracks , the viewpoint will change , potentially confusing the player . The player will immediately drop a SeeD rank if s / he decides to venture out of the tomb before his / her objective is fulfilled . Centra Ruins . The Centra Ruins is on the Centra continent . Upon entering the ruins , a timer begins and the party must find a series of red gemstones and place them in the eyes of statues to acquire the secret code to access the room where Odin is fought . The Tonberry King also appears randomly once 20 or more Tonberries have been killed . Defeating him earns the player Tonberry as a Guardian Force . Deep Sea Research Center . The Deep Sea Research Center is a hidden island far out in the middle of the ocean , in the very southwest corner of the world map . It is an abandoned , half - sunken laboratory formerly used to research draw effects . In the first area the player must face Bahamut , and after defeating him and earning him as a Guardian Force , the player can advance deeper into the ruins after leaving and returning . Some of the toughest opponents are fought on the way to the bottom , and on the last floor the player faces Ultima Weapon , who has the most powerful Guardian Force , Eden . " Final Fantasy X " . Cavern of the Stolen Fayth . The Cavern of the Stolen Fayth is located in a gorge to the north of the Calm Lands , near the entrance to Mt . Gagazet . The cave hides a fayth that legend says was stolen long ago to prevent summoners from completing their pilgrimage . At the end of the cavern , the players fight a boss , and get the chance to recruit Yojimbo as an aeon for Yuna . In the International and " HD Remaster " versions , the party can fight Dark Yojimbo after obtaining the aeon , leaving and reentering the dungeon . Omega Ruins . The Omega Ruins is a large dungeon located within a small group of islands to the east of Spira ' s main continent . Unlike many of the other locations in the game , the cave must be mapped by the player . At the end of the cave , two deadly bosses await the party : Ultima and Omega Weapons . " Final Fantasy X - 2 " . Because of the game ' s non - linear nature many areas and missions are optional . Completing most of the areas is still needed for 100 % story completion , although some areas are truly optional , and do not affect story completion . Ruins Depths . The Ruin Depths is an optional dungeon in the Calm Lands , situated behind and on a lower level than the Calm Lands Ruins . Unlike most areas in " Final Fantasy X - 2 " , the Ruin Depths does not have a mini - map , and contains some rare and unique treasures . The dungeon must be unlocked to enter in a complicated process of chocobo raising and exploration . The boss of the area is the Anything Eater . Once it is defeated , all five sets of locked doors are unlocked ; once they are manually opened , the final door giving access to the Amazing Chocobo is unlocked . A Garment Grid with the constant ability of Break HP Limit is the prize for getting to the Amazing Chocobo . The Ruins are not part of 100 % completion or the main quest . Fiend Colony . The Fiend Colony is an optional dungeon located on the Mi ' ihen Highroad . The player must dispatch a level four or five chocobo to the highroad from Clasko ' s Chocobo Ranch during Chapter 5 to access it . To travel through the dungeon , the player will need to destroy stone walls with bombs . Once the player reaches the back of the cave , they will fight the King VERMIN ! . Defeating him gets the party a new Garment Grid . Completing Fiend Colony is not needed for 100 % story completion . Den of Woe . Den of Woe is a hidden cave in the Mushroom Rock Ravine accessed if ten Crimson Sphere s are collected . Many of the spheres have special requirements to be obtained and are well hidden . The Den of Woe contains no treasure , but has some boss battles . Although Den of Woe is a sidequest , unlocking and entering the Den is necessary for 100 % completion . Via Infinito . Via Infinito is a 100 - floor dungeon beneath Bevelle . In the final cloister the party can challenge the game ' s superboss , Trema . For each cloister block of 20 floors , there are about 6 level designs which appear at random as each one is completed . The dungeon is swarming with monsters , and equipping a Charm Bangle for No Encounters will have no effect . Every oversoulable fiend , except for the Georapella and Precepts Guard , can be found here . Valuable spheres and accessories can be obtained from the defeated bosses . Completing Via Infinito adds to story completion . " Final Fantasy XII " . Necrohol of Nabudis . The Necrohol of Nabudis was once the capital of the Kingdom of Nabradia , but its remains have become corrupted by the thick Mist that covers the region . The location is not part of the main storyline , and houses the game ' s ultimate weapon , the Zodiac Spear . The player can access the area as soon as the Dawn Shard has been acquired , which means that the game ' s ultimate weapon can be acquired fairly early . The Esper Chaos resides in the Necrohol , as do some marks and rare game . However , the party cannot obtain Chaos until they have at least reached Archades , as one of the items needed to reach him requires a miniquest to be completed there . Great Crystal . Even though Great Crystal is visited as part of the storyline , only a small part of it is mandatory . If the player returns after having obtained the Treaty - Blade , they can travel into the deepest parts of the crystal . The area has no in - game map , and the interior is like a maze with many dead ends and paths that need to be unlocked . The Esper Ultima and the superboss Omega Mark XII reside within the crystal , as well as several rare game . Henne Mines . Henne Mines is a mandatory story location , but its true depths can only be explored after obtaining ten Espers and asking the geomancer in Jahara to open the locked gate within the mines . At the mines the player will encounter some of the toughest regular monsters in the game , and at the end of the mines , battles the ultimate Esper , Zodiark . Midlight ' s Deep . Midlight ' s Deep is a secret dungeon in the US and PAL versions that features the hardest challenges in the game and is located in the Keep of Forgotten Time . It consists of ten levels and the dungeon can be left at any time , though the party must start back at the first level when reentering . On the tenth and final floor resides the superboss Yiazmat . After completing Midlight ' s Deep , Vaan ' s Anastasia sword gets a boost of + 10 in all stats . The stat boosts are cumulative if the player completes Midlight ' s Deep again . " Final Fantasy XIII " . Faultwarrens . The Faultwarrens is an optional location on Gran Pulse . It is where the fal ' Cie Titan resides breeding increasingly powerful monsters and pitting them against the party . Some of the tougher missions are fought here , for a variety of prizes . " " . The Ultimate Lair is located in the Dead Dunes and can be accessed on the " " via a new Cactuar statue that appears outside the Ruins East Gate . The Lair is full of Last One s , and is imperative to visit to complete a certain side quest , as it is the only location during a regular playthrough where Meonekton Ω will spawn due to having to kill a prohibitively high number ( 65 , 535 ) of the regular monster otherwise . If Lightning already drove a particular species into extinction , those specimens do not appear . Within the Ultimate Lair , the game clock doesn ' t stop , even during battle , and Chronostasis is disabled . Lightning must keep moving to reach the deepest level . After defeating the enemies on each level she gains access to warp devices that lead to lower floors . On the last floor she can battle the game ' s superboss , Ereshkigal . " Final Fantasy XIV " . Most dungeons are not part of the main storyline and are unlocked via sidequests . Thus far all Hard modes of dungeons aren ' t mandatory , including those based on dungeons that were part of the main storyline . List of bonus dungeons : A Realm Reborn | width = " 33 % " align = " left " valign = " top " | A Realm Reborn ( continued ) | width = " 33 % " align = " left " valign = " top " | Heavensward < / div > < / div > " Final Fantasy XV " . Pitioss Ruins . Pitioss Ruins is an unusual dungeon hidden among the mountains to the north - east of the Rock of Ravatogh that can be accessed after the Regalia has been upgraded to the Regalia Type - F . Unlike other dungeons in the game ( and other dungeons throughout " Final Fantasy " as a series ) , Pitioss features no enemies . Instead , Noctis must enter this dungeon alone and complete a series of complex puzzles . For completing the challenging dungeon players are rewarded with the Black Hood . Sealed dungeons . Eight of the dungeons found throughout the game have sealed doors within their depths . These doors contain a secondary dungeon that features less complex dungeons and significantly stronger monsters to battle . These doors can be opened after completing the main game , as well as having already completed the basic form of the dungeons containing these doors . Players must visit Meldacio Hunter HQ and speak to Ezma who will present Noctis and his friends with the key to open the sealed dungeon doors . List of dungeons featuring sealed doors : When the party first comes across a locked door to one of the bonus dungeons , Prompto Argentum remarks that he wishes they had a key that can unlock any door " just like in video games " . " Final Fantasy Tactics " . Midlight ' s Deep . Midlight ' s Deep is located on an island east of the Port City of Warjilis . It consists of ten levels of caves , and is home to the most difficult enemies and the best treasure through the Treasure Hunter ability . From the start , only one of the ten levels can be accessed . To get deeper , the player must fight a battle , all of which function like random battles . Simply defeating every enemy on the screen will not work , instead , the player must find a passageway to the next level that is always hidden in one of five different squares on each floor . To find the exit , a unit needs to step on that square . The tenth level holds a regular storyline battle with the secret Lucavi demon Elidibus , who uses the Zodiac summon which can only be learned from him . Brightmoon Tor . Some of the strongest enemies in the game reside in these dungeons . At the top of each Brightmoon Tor location is a watch that have enemies at level 90 and above . Although the items the dungeons contain may only be obtained once , multiple attempts can be made to retrieve them . If one failed to notice them the first time , or simply did not have the required equipment , one can try again . " Final Fantasy Type - 0 " . Tower of Agito can be entered via the airship , " Setzer " , and boasts a hefty challenge . The player must complete five series of battles in which they must defeat 100 of a specific enemy , all of whom are at Level 128 . Players may access relic terminals prior to entering each challenge , as they will be unable to leave the area until all 100 enemies are defeated . Rare accessories are available , with the final prize at the top being the game ' s best accessory , the Agito Insignia . " Final Fantasy Legend II " . There is one bonus dungeon in the game , Nasty Dungeon , and it lives up to its name . The monsters comes in a large variety of groups , and the dungeon branching pathways with no real indication as to which path is the correct one . Enemy groups can easily reach up to fifteen , more or less monsters per battle , and surprise attacks can become quite a constant threat inside this dungeon . But the treasure found inside is well worth the player ' s effort . Unlike many bonus dungeons , the Nasty Dungeon is not strictly optional : the player must enter it to collect the Pegasus just past the entrance . A fairy posted by the chest will warn the player about the danger , advising them to take the MAGI and leave . " Final Fantasy Legend III " . There are quite a number of optional dungeon to explore , and they are found in various areas . But some of them becomes inaccessible after a certain point . The dungeons are fairly simple to navigate and contains valuable treasures . List of optional dungeons : Holy Tree Tower , Moonsand Ruins , Mysterious Lighthouse and Trial Tower become available after the player obtains the Master Key . Each tower is 100 floors tall with special floors every 10 floors where the player can leave the tower to save . Sometimes the special floors have bosses or a merchant or a treasure chest . Some of the best equipment can only be obtained as random treasures in the bonus dungeons . " Bravely Default " and " " . In " Bravely Default " , Dimension ' s Hasp is an optional dungeon located at the Kustra Archipelago , and becomes available after speaking to either Lord DeRosso in the " Finale " or Sage Yulyana in " The End " , although the Sage will also unlock the seal to access the 10th and final floor . Each floor reuses a map from a previous dungeon , and is home to all the game ' s enemies , as well as equipment that includes the strongest weapons of each type . At the end of the final floor is a secret boss battle against the Adventurer and the Comrade . In " Bravely Second " , after Dimension ' s Hasp is destroyed by Ba ' al Diamante , Yulyana conjured three new optional dungeons in the Ruins of Centro Keep in Caldisla , Mount Fragmentum in the Yulyana Region , and the Underflow under Eisenberg . Like the previous game , the dungeons are home to the game ' s enemies and hold the strongest weapons which are protected by dragons . At the end of Dimension ' s Caludron is a secret boss battle against the Adventurer and the Comrade .