Located in the nothern mountains of the northeastern landmass.
The first door on level 1 leads directly to the Earth Crystal, while the rest of the levels eventually exit through the world map to the Crystal Tower.
Level 1: Elixir
Level 3:
Level 4:
Level 5:
Level 1 (room): Titan
Levels 2-3 & 5: Bone Dragon
Level 5: King Behemoth
Very rare, extra powerful.
Optional dungeon accessible through a door in the Crystal Tower after completing Doga's Grotto.
Geomancers are quite powerful here, frequently casting Shadowflare that deals 9999+ damage at job level 50.
Level 7 contains a two-way portal to a rest area with no enemies, revive and recovery wellsprings, a level 8 magic and ultimate summon shops, and an armor shop.
Level 1:
Level 2:
Left room: White Musk
Right room: White Musk, Phoenix Down, Chocobo's Wrath
Level 3:
You have to enter the level from the bottom left exit of level 2.
Level 4: Moonring Blade
Level 5:
Once unlocked, can be found underwater directly west of the very tip of the Dalg continent (where Doga's Manor is). See the side-quest section on how to unlock this dungeon.
This is an exceedingly difficult area with the strongest enemies in the game, meant for grinding levels and Onion Knight equipment. You will need to level up a lot to stand a chance against the boss (fighting him at level 75 is a considered a low level challenge), and once you're strong enough to defeat him, the rest of the game (including the final boss) will pose very little challenge, if any.