The Dungeons that are worth roughly 7 HT (1 for an optional puzzle, 2 for the Miniboss, 4 for the Dungeon).
Ikana Canyon was once a wasteland cursed into undeath.
Volga's Palace sits in the center of a lake of lava, adjacent to Subrosian cities and the Tower of Hyrule, the place where the mirror between Hyrule and Subrosia sits.
Whenever a Zola is born, it gets exiled to Zola's Dungeon.