The largest ocean on our planet is the Pacific Ocean, which is also the deepest ocean. The Pacific Ocean covers approximately 63 million square miles and contains more than half of all the water on earth. It is followed in size by the Atlantic, the Indian, the Southern, and the Arctic Oceans. Depending on when you were raised, you may have learned there were either four or five major oceans. Before the year 2000, the significant oceans were the Pacific, the Atlantic, the Indian, and the Arctic. In 2000, the International Hydrographic Organization officially adopted the Southern Ocean as the fifth ocean, making up the southern portions of the Pacific, Atlantic, and Indian Oceans and surrounding Antarctica. The Southern Ocean is sometimes known as the Antarctica Ocean.