Covering approximately 63 million square miles and containing more than half of the free water on Earth, the Pacific is by far the largest of the world's ocean basins. All of the world's continents could fit into the Pacific basin.
The Pacific is the oldest of the existing ocean basins. Its oldest rocks have been dated at about 200 million years. The Pacific basin is referred to as the "Ring of Fire" due to intense earthquake and volcanic activity occurring near areas of tectonic plate subduction (where one tectonic plate is forced under another).
The Atlantic basin is the second largest basin, followed by the Indian Ocean basin, the Southern Ocean, and finally the Arctic Ocean basin.