Five oceanic divisions are usually recognized: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Antarctic/Southern Ocean, and the Arctic Ocean; the last two listed are sometimes consolidated into the first three. Learn about the ocean and its inhabitants, from sea turtles to whales. The ocean is essential to life on Earth.

Understanding the Context

It covers more than 70% of our planet and holds 96.5% of all water. It regulates our climate, generates half of Earth's oxygen, and is home to millions of species. Ocean, continuous body of salt water held in enormous basins on Earth’s surface. There is one ‘world ocean,’ but researchers often separate it into the Pacific, Atlantic, Indian, Southern, and Arctic oceans.

Key Insights

Curious about the oceans, their ecosystems, and the vital role they play in sustaining life on Earth? Explore OCEARCH Ocean Facts to learn how the seas regulate climate, provide food and oxygen, and support incredible biodiversity—from coral reefs to the open ocean. Explore all 5 ocean zones interactively from the sunlit surface to 11,000m deep. This deep ocean explorer lets you discover 18 marine creatures, bioluminescence, and 3D underwater terrain. For much of recorded history, Earth was said to have four named oceans: the Atlantic, Pacific, Indian, and Arctic.

Final Thoughts

However, many countries—including the United States —now recognize the Southern (Antarctic) Ocean as the fifth. To find ways to protect the ocean from pollution and the effects of climate change, scientists from all over the world are cooperating in studies of ocean waters and marine life. As one component of the interconnected World Ocean, it is connected in the north to the Arctic Ocean, to the Pacific Ocean in the southwest, the Indian Ocean in the southeast, and the Southern Ocean in the south. Other definitions describe the Atlantic as extending southward to Antarctica.