The largest ocean in the world is the Pacific Ocean. Covering more than 63 million square miles, it extends from the Arctic Ocean in the north to the Southern Ocean in the south, and is bordered by Asia and Australia on the west and the Americas on the east. The Pacific Ocean is not only the largest but also the deepest ocean, containing the Mariana Trench, which reaches depths of about 36,000 feet. The ocean plays a critical role in regulating the Earth's climate and weather patterns, as well as being a vital resource for marine biodiversity, trade routes, and fishing industries.