Great Flood
The Great flood, as described in The Wind Waker, was the work of "the gods." This event occured sometime after the happenings of Ocarina of Time. The survivors found refuge on the high mountain tops, which became islands and the flooded kingdom later became known as the Great Sea. After many generations, Hyrule was all but forgotten.
At the end of The Wind Waker, the king of Hyrule, Daphnes Nohansen Hyrule, tells Link and Princess Zelda to go and find a new land. Many fans believe, this new land is the Hyrule that is featured in later games in the timeline. Another theory arose from a statement by the Deku Tree, "Forests have great power, they can change one tiny island into a larger island. Soon, a day will come when all islands are one, connected by earth and grove."
There are many theories, but at this time, it is still unclear which one of them is correct.
Its also possable that The Moon from termnina is hyrule's moon but the godessess had to move it to Termina and then created a second moon, and as the grew closer the water pressure rose
