Subrosia

From Zelda Wiki.org

Subrosia is a subterranean lava world beneath the world of Holodrum. The inhabitants, Subrosians, can access all parts of Hyrule from their land. To outsiders, this land is only accessible from Holodrum through strange portals.

The Temple of Seasons caused quite a ruckus among the Subrosians when it sank into their homeland. It is not known what used to reside where the Temple of Seasons landed, although one Subrosian mentions that it hit the East Plaza.

The currency used in Subrosia is 'Ore Chunks', which can mainly be found by chopping down bushes or digging up the ground. The ore can be used to buy Gasha Seeds, hearts, more ore and other things in a market in Subrosia.

You can also obtain Dimitri's Flute here, a item used to summon Dimitri. Also, the only dungeon here is the final one in the game: the Sword & Shield Maze.