Underwater Temple is a unique dungeon location in Romancing SaGa: Minstrel Song. The Temple belongs to Yucomb, God of the Sea and is home to the Black Diamond, one of the legendary Fatestones. You can only access the temple once per playthrough, as it is only available during the quest "The Underwater Temple". If you completed the "Stolen Nymphs" quest earlier then Marina will search for you in coastal towns. She will mention Yucomb wanting your help in gaining the Diamond of Darkness, and trasnport you under the Black Sea to the temple. The temple is full on monsters and dangers and Marina is forbidden to enter, leaving you to explore it on your own.