Great Hyrule Forest

Great Hyrule Forest is a lava dome, in the middle of a large caldera filled with water. An extinct volcano, part of the Eldin mountains, west from the active Death Mountain stratovolcano.

The dome takes it's name from the forest that has grown above, helped by the volcanic fertile soil. The caldera is way larger than the summit caldera of the nearby Death Mountain, and when it was active, it was prone to far more violent eruptions than the Death Mountain, at the point that it was unable to grow a proper volcanic edifice.