The Pacific Ocean is the biggest and deepest ocean in the world, spanning nearly one-third of Earth’s surface and covering around 162 million square kilometers. Which Ocean Is the Largest? A map of the world's oceans. The Pacific Ocean ranks as the largest of the world’s oceans, followed by the Atlantic Ocean, and subsequently the Indian Ocean. Even before the Europeans sighted the vast ocean, pre-historic communities, such as the Austronesian peoples, had sailed across it. Etymology In 1519, the Portuguese navigator, Ferdinand Magellan began crossing the Atlantic Ocean in search of a western route that would lead him to the Spice Islands through ... The Pacific Ocean reigns supreme as the largest ocean on Earth, dwarfing all others in both size and depth. Spanning an astounding 63 million square miles (165.25 million square kilometers), it covers approximately 30% of the Earth’s surface and contains more than half of the planet’s free water. Ocean – the four to seven largest named bodies of water in the World Ocean, all of which have "ocean" in the name (see: Borders of the oceans for details). Sea has several definitions: [a] A division of an ocean, delineated by landforms, [6] currents (e.g., Sargasso Sea), or specific latitude or longitude boundaries. This includes but is not limited to marginal seas, and this is the definition used for inclusion in this list. A marginal sea is a division of an ocean, partially enclosed by ...