The Pacific Ocean is one of Earth's seas and the overall largest sea on the planet.
During the 2012 apocalypse, the Pacific Plate destabilized which caused California to sink beneath the waves of the Pacific. When the Earth's crust shifted at 1.22 degrees, the Pacific Ocean was moved from its original position to a new position between the place where the North American and South American continents originally were.
Among the Japanese seaboard, the Genesis ship was hit by a gigantic tsunami when the Worldwide Flooding occurred in the Pacific. Asia was now at the Pacific Ocean's original position, which allowed the Curtis and Karpov group to land in Cho Ming Valley when they were heading for the Arks.
After the apocalypse ended, the new position of the Pacific Ocean continued to remain in its current position when the Arks set sail for the risen continent of Africa (which did not suffer extreme damage).