The Pacific Ocean is the largest body of water on the planet. It stretches from the Arctic Ocean in the north to the Southern Ocean in the south, and it is bordered by Asia and Australia in the west and the Americas in the east. With an area of 63.8 million square miles, the Pacific occupies approximately a third of the Earth's surface, about 46 percent of the planet's total water surface and is dramatically larger than all of the land masses on Earth combined. The temperature varies depending on the area, with freezing temperatures at the poles and temperatures of around 86 degrees Fahrenheit at the equator. There are more than 25,000 islands dispersed throughout the Pacific, many more than the number of islands in all other oceans combined.
The second-largest ocean on the planet is the Atlantic, stretching from North America and Europe in the north to between South America and Africa in the south, thus ranging from the Arctic to the Antarctic. With a size of approximately 29.7 million square miles, the ocean covers about 20 percent of Earth's surface and about 26 percent of the planet's total water surface area. Some of the Atlantic's water supply is provided by large rivers such as the Amazon, Niger and Congo. The average depth of the Atlantic is 12,800 feet, and the ocean floor is made of huge mountains, hills, valleys and tablelands that are similar to those on dry land.
The Indian Ocean is the third-largest body of water, bordered on the west by Africa, on the east by Indochina, on the north by the Indian subcontinent and on the south by the Southern Ocean. The size of the Indian Ocean is about 26.5 million square miles, which occupies about 20 percent of the planet's water surface area. Islands -- such as Madagascar, Comoros and Sri Lanka -- dot the continental rims, and some of the large rivers that flow into the ocean include the Ganges, the Indus and the Zambezi.
With a total size of approximately 7.9 million square miles, the fourth-largest body of water is the Southern Ocean, also known as the Antarctic Ocean. This ocean encompasses the entire southern waters area of the World Ocean and wraps around the frozen continent of Antarctica. Unlike all other oceans, the largest boundary of the Southern Ocean is not a land mass but is formed by the convergence with other oceans such as the Pacific, Indian and Atlantic. The ocean was formed approximately 30 million years ago as a result of Antarctica and South America splitting apart due to continental drift, making it the world's youngest ocean.