Created by Nintendo as a new setting for Link to explore, The Great Sea became the overworld of both The Wind Waker and Phantom Hourglass. It is the first overworld in the series where Link requires a vehicle to explore properly. The sea is dotted with dozens of islands, the tips of the mountains that Hyrule used to have, where people live and colonize. The game's characters repeatedly inform you that there are no fish dwelling in the sea, although there are Gyorgs, Octoroks, Big Octos, Sea Hats and Fishmen roaming it's waters. These quotes support the theory that the Rito evolved from the Zora, as it was impossible for them to survive in the salt-water ocean.
The setting became popular and was used as a location in the sequel to Wind Waker, Phantom Hourglass. It was also added as a stage for Super Smash Bros. Brawl.