|A strong, cold ocean current swept down from the north in the Eastern Ocean, pushing all ships horribly off course. Ships that traveled east and returned reported nothing but open ocean and vile sea monsters...|
|—Lore describing Green Isle attempts to navigate the Great Ocean.|
The Great Ocean was an ocean separating the Old Continent in the west from the Great Continent in the east. The ocean also contained a number of islands, including the Green Isle, Morogor, and the Naga archipelago. Near to its shore across the Great Continent lay a number of islands, including the Three Sisters, the Island of Alduin,, the Shimmering Isle, and Bilheld. The Great Ocean had perilous sailing conditions, especially to the east of the Green Isle, where a strong current pushed ships south. The people of the Green Isle originally called this part of the ocean the Eastern Ocean.
The Great Ocean contained merfolk cities, including Jotha, the merfolk calling the sea the Western Ocean. It was also home to the nagas, who took advantage of sailors who shipwrecked on their archipelago. The ocean was also known to be inhabited by various sea monsters.
Despite the severe sailing conditions, humans managed to reach the Green Isle from the Old Continent. Also, with the help of Lady Jessene, the First Crown Prince of Southbay was able to lead the first known voyage from the Green Isle to the western shores of the Great Continent by sailing aggressively to the northeast. This achievement was later repeated by Prince Haldric, who arrived at the Great Continent with a large number of refugee ships.
- A Summer of Storms, The Rise of Wesnoth
- Peoples in Decline, The Rise of Wesnoth
- Rough Landing, The Rise of Wesnoth
- Epilogue, Liberty
- Slipping Away, Secrets of the Ancients
- Invasion, Dead Water
- Cliffs of Thoria, Heir to the Throne
- Southbay in Winter, The Rise of Wesnoth
- A New Land, The Rise of Wesnoth