Summary
Salt water covering about 71 percent of Earth, home to most of the planet's living space.
In depth
The ocean holds about 97 percent of Earth's water, average depth 3.7 km, and absorbs about 90 percent of excess heat and a quarter of CO2 emissions. It produces roughly half of the oxygen we breathe through phytoplankton. Less than 25 percent of the sea floor is mapped in high detail.
The ocean's three-dimensional habitat is the largest on Earth. Physical properties such as density and pressure shape life. Ocean circulation redistributes heat.
Key idea: oceans regulate climate and supply oxygen, food and resources.
Oceans cover about 71 percent of Earth's surface, hold roughly 97 percent of its water and provide over 95 percent of its living space by volume. The five basins (Pacific, Atlantic, Indian, Southern and Arctic) average about 3.7 km deep and reach nearly 11 km in the Mariana Trench.
Oceans regulate climate by absorbing heat and carbon dioxide, produce about half of the oxygen we breathe through phytoplankton, drive weather and supply food, medicines and transport. Seawater has an average salinity of about 35 parts per thousand, mostly sodium and chloride.
Example: the ocean has absorbed over 90 percent of the excess heat from global warming.
Frequently asked questions
What is Oceans?
Salt water covering about 71 percent of Earth, home to most of the planet's living space.
Which area of biology covers Oceans, and how advanced is it?
Oceans is one of the 54 topics in Marine & Environmental Biology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Thermohaline Circulation, Global Warming, Upwelling.
Why does Oceans matter?
Ocean health is tied to human survival, yet less than a quarter of the seafloor is mapped in high detail.
Can you give an example of Oceans?
The Mariana Trench is nearly 11 km deep.
What should I learn before Oceans?
Oceans is a Beginner topic, so no earlier topic is required. Other Beginner topics in Marine & Environmental Biology that pair well with it include Ocean Zones, Plankton, Coral Reefs.
What topics are related to Oceans?
The closest topics to Oceans are Thermohaline Circulation, Global Warming, Upwelling, Biological Pump. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Oceans?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Oceans. To practise the whole of Marine & Environmental Biology, use the Marine & Environmental Biology quiz.
How is Oceans different from Thermohaline Circulation?
Oceans: Salt water covering about 71 percent of Earth, home to most of the planet's living space. Thermohaline Circulation: A global ocean conveyor driven by differences in temperature and salinity that distributes heat. Read both side by side and note what each one explains.
How should I study Oceans step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Thermohaline Circulation and explain the difference aloud. Finally, take the Marine & Environmental Biology quiz and come back to this page for any question you miss.