The Pacific Ocean is the biggest ocean on Earth by a wide margin, stretching across 168,723,000 square kilometers and about 65,144,000 square miles, according to a new ranking of the planet’s five named ocean basins. It holds roughly 46.6 percent of the global ocean, more than any other basin on the list.
That ranking is getting attention now because people still reach for a simple answer to a basic question: which ocean is largest, and by how much? The Pacific is not just first on size. It also spans the planet’s full north-to-south reach, sits between the Arctic and the Antarctic, and carries about 25,000 islands across 135,663 kilometers of coastline, making it the broadest measure of the ocean most readers picture when they think of open water.
The numbers also underline how much of Earth is water in the first place. About 71 percent of the planet’s surface is covered by saltwater, and roughly 96.5 percent of all water on Earth sits in the ocean. But there is technically only one global ocean, a single body of water uninterrupted by land. For maps and convenience, it is broken into five basins: the Pacific, the Atlantic, the Indian, the Southern and the Arctic.
Placed beside the Pacific, the Atlantic looks smaller but still immense. It covers about 85,133,000 square kilometers, or 32,870,000 square miles, with 111,866 kilometers of coastline and an average depth of 3,646 meters. Its deepest point is the Milwaukee Deep at 8,380 meters inside the Puerto Rico Trench. The Pacific remains larger, deeper on average at 3,970 meters, and it contains the Mariana Trench, where the Challenger Deep drops to about 10,994 meters below the waves.
That is where the neat ranking runs into the messier reality of ocean geography. The oceans have been divided differently over the centuries for scientific and political reasons, and the borders people use on maps are more convention than seam. The Pacific’s 50.1 percent share of all the water in the global ocean is a reminder that the five-name system is useful, but it is still a human way of sorting one continuous sea.
The scale of that sea has also drawn people far beyond the shoreline. Victor Vescovo became the first person ever to reach the Atlantic Ocean’s deepest point in December 2018, a feat that showed just how extreme these basins can be even when they are grouped under familiar names. For now, the Pacific stands alone at the top of the list, and the unanswered question is not which ocean is largest, but how much more of the planet’s underwater terrain remains to be measured in the same exact way.
