The Indian Ocean is the third-largest of the world's five oceanic divisions, covering 70,560,000 km 2 (27,240,000 sq mi) or approximately 20% of the water area of Earth's surface. [4] It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by the Southern Ocean, or Antarctica, depending on the definition in use. [5]