Earth's Ocean

Earth's ocean covers more than 70% of our planet's surface. There are five major ocean basins: the Pacific, the Atlantic, the Indian Ocean, the Arctic Ocean, and the Southern Ocean that surrounds Antarctica.

Seawater is salty. Anyone who has taken a gulp of water while swimming in the ocean knows that. The saltiness of the water is called salinity. Salt is dissolved in the seawater. There are other minerals and gases dissolved in seawater too.

Ocean water is always moving. It moves around surface ocean currents in the top part of the ocean. It also moves from the deep ocean to shallow areas by upwelling and moves back to the deep ocean by downwelling. Currents along coastlines move water too. Each day ocean water moves with the tides, shifting where the water meets the shore.

Over a long time water moves from the deep ocean to shallow ocean and back again to the deep in the global ocean conveyor. As Earth’s climate warms this pattern might change.

The height of the ocean surface is called sea level. Over a long time, sea level can change for a number of reasons. Today sea level is rising because Earth’s climate is getting warmer.

Coral reefs are affected as the ocean changes because of global warming, pollution, and other changes. The ocean is becoming more acidic, which is harmful to corals and other marine life.

Last modified February 15, 2011 by Jennifer Bergman.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

The Southern Ocean

The Southern Ocean is sometimes known as the Antarctic Ocean or South Polar Ocean. It surrounds Antarctica in the South Polar Region. The Southern Ocean is a bit different from other oceans. Other oceans...more

Antarctica

Antarctica is the coldest, windiest, and driest continent on Earth. It is about one and a half times the size of the United States. Almost all of Antarctica is covered with a thick layer of ice called...more

Salinity

Almost 3/4 of the Earth is covered with water. Almost all of that water is in the oceans. Have you ever been swimming in the ocean? If you have and you accidentally got water in your mouth, you know the...more

Surface Ocean Currents

The water at the ocean surface is moved by powerful wind. The wind is able to move the top 400 meters of the ocean. This moving water is called surface ocean currents. Surface ocean currents form large...more

Ocean Upwelling

There are places in the ocean where water from the deep sea travels up to the surface. These are called areas of upwelling. The deep waters can have a large influence on marine life and the climate too....more

Currents at the Coast

When waves get to the beach at an angle, water moves along the coast in a longshore current. Longshore currents grow stronger when the waves come towards the beach at a large angle, if the waves are large,...more

Tidewater

Have you ever walked along the same beach at different times during the day? Did you notice that sometimes the water was higher up on the beach than at other times? Changes in the height of ocean water...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA