The Stone Castle is located at E-3 NW, in the Zahhab Region in Endless Ocean 2. Located near Long Fissure, this area is populated by several shoals of smaller coral reef fish, as well as several Leopard Whiprays that float nearby.

The Castle is a large rock formation covered in all sorts of coral. Holes and cave-like structures have been hollowed out of the stone over time by the ocean currents and other factors, making the whole formation resemble a complex architectural design rather than a natural one, and thus granting the structure its name.

The Caiman Relic (the object that summons King Gigide to the Twilight Temple) is found here.