The Hidden Temple is a dungeon of the Fitzgald region in Tales of Destiny. In Tales of Destiny 2, which takes place 18 years after the events of Tales of Destiny, the location is no longer accessible.
After Hugo Gilchrist begins using the Eye of Atamoni to power Belcrant and revive the Aethersphere, the protagonists consult with Marius Raiker, from whom they learn that a device known as the "R Key" is required to grant Radisrol flight capability. They board the seabound Radisrol ship and travel to Fitzgald's continent, where they discover the Hidden Temple in a lake near Lienea. Inside, the group is forced to use their Swordians to open the chamber doors within, each Swordian Master remaining behind with their Swordian while the remainder of the group proceeds forward. At the end of the dungeon, Stahn Aileron joins the non-Swordian-wielding members of the group in defeating the guardian of the R Key, securing it before leaving and returning to Radisrol as Hugo initiates the second attack on the Er'ther Lands.