A huge set of underground caves under Lazulis City. They are accessed by climbing down a well in the south of the City. They're connected with the other sets of Caves dug by the Reptids under Lazulis Island.
It's the home of the Reptids' queen, Queen of the Abyss, and is where the Reptids have stored all their treasures. It's well guarded by groups of Reptids and mines planted to stop intruders. The Reptids here are well organized, even better than any others found in the game.