The ocean in medieval times was a thing of great mystery to the ordinary medieval peasant. However to the explorers, the church and the educated the sea was a dangerous place. The ocean began to fascinate people in the time of the early Greeks. The Titans ruled the earth in the beginning, and Oceanus, son of Uranus and Gaea was one of them.

"In him [Oceanus] Homer salutes the essence of all things, even the Gods, and regards him as a divinity whose power was inferior to none but Zeus'"

He was the father of all the rivers and lakes of the world. But then the Olympians rebelled against the Titans, Zeus drove Cronus into the western ocean. When Zeus had taken his place as head of the gods, not even the oceans tides could defy him.

According to the Odyssey there were remote paradise islands in the...