Borders of the oceans

The borders of the oceans mark where Earth's oceanic waters end. Deciding how many oceans exist depends on the rules we use. The five main oceans, from largest to smallest, are the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern (Antarctic) Ocean, and Arctic Ocean.

Smaller parts of the oceans have special names like seas, gulfs, bays, and straits. Scientifically, an ocean is a place where the rocky floor under the water, called oceanic crust, is covered by water.

You can learn more about the seas that are part of each ocean in the List of seas on Earth.

Overview

The world's oceans are all connected and form one big body of saltwater, often called the World Ocean. The main parts of this global ocean are defined by the continents and other landforms. The five main oceans, listed from largest to smallest, are the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern (Antarctic) Ocean, and Arctic Ocean. Smaller parts of the oceans have different names like seas, gulfs, bays, and straits.

The Pacific Ocean is the largest, stretching from the Southern Ocean to the Arctic Ocean between Australia and Asia, and the Americas. The Atlantic Ocean is the second largest, reaching from the Southern Ocean to the Arctic Ocean between the Americas, Africa, and Europe. The Indian Ocean is the third largest, extending from the Southern Ocean to India, the Arabian Peninsula, and Southeast Asia, between Africa and Australia. The Arctic Ocean is the smallest, touching North America, Scandinavia, and Siberia, and is partly covered by sea ice. The Southern Ocean surrounds Antarctica and is also partly covered in sea ice.

Arctic Ocean

The Arctic Ocean is a big body of water that covers much of the Arctic area. It touches Northern America and Eurasia. Sometimes, people think of it as part of the Atlantic Ocean.

There are different ways people decide where the edges of the Arctic Ocean are. One group, the International Hydrographic Organization, has specific lines to show where it ends, but these lines do not include smaller seas nearby, even though those seas are often thought of as part of the Arctic Ocean. Another group, the CIA, has a different way of drawing these edges.