The ocean covers 70 percent of Earth’s surface. It contains about 1.35 billion cubic kilometers (324 million cubic miles) of water, which is about 97 percent of all the water on Earth. The ocean makes all life on Earth possible and makes the planet appear blue when viewed from space. Earth is the only planet in our solar system that is definitely known to contain liquid water.
Oceans are huge bodies of salt water. They are home to many aquatic animals like fish, dolphins, whales, squid, turtles, and octopuses.
Ocean salt primarily comes from rocks on land and openings in the seafloor. Salt in the ocean comes from two sources: runoff from the land and openings in the seafloor. Rainwater that falls on land is slightly acidic, so it erodes rocks. The eroded minerals from these rocks, including salt, are carried into the ocean by rivers and streams.
Why are oceans important?
Oceans provide food, regulate our climate, and generate most of the oxygen we breathe. They also serve as the foundation for much of the world’s economy by supporting sectors such as tourism, fisheries, and international shipping.
The ocean plays a vital role in climate and weather. The sun’s heat causes water to evaporate, adding moisture to the air. The oceans provide most of this evaporated water. The water vapor condenses to form clouds, which release their moisture as rain or other forms of precipitation. All life on Earth depends on this process, called the water cycle.
The atmosphere receives much of its heat from the ocean. As the sun warms the water, the ocean transfers heat to the atmosphere. In turn, the atmosphere distributes the heat around the globe.
Because water absorbs and loses heat more slowly than land masses, the ocean helps balance global temperatures by absorbing heat in the summer and releasing it in the winter. Without the ocean to help regulate global temperatures, Earth’s climate would be much more extreme.
Why are oceans blue?
The ocean is blue because water absorbs colors in the red part of the light spectrum. Like a filter, this leaves behind colors in the blue part of the light spectrum for us to see. The ocean may also take on green, red, or other hues as light bounces off floating sediments and particles in the water.
Although the ocean is one continuous body of water, oceanographers have divided it into five principal areas: the Pacific, Atlantic, Indian, Arctic, and Southern Oceans.