About 3.5 billion years ago the ocean gave rise to the first life on Earth. Today no matter where you live, it shapes and sustains your life-and all life around you.

The Milstein Hall of Ocean Life. © Denis Finnin / AMNH

The ocean is vast, covering more than two-thirds of the planet. Beneath its waves lies an amazing diversity of habitats, from coral reefs to polar seas. Each supports an astonishing array of life. And the ocean provides oxygen to the atmosphere and drives the world's climate—so all life on Earth depends on the ocean for survival.

Although we learn more about the ocean every year, many mysteries remain. Less than five percent of the ocean has been explored. And for every new species that we recognize, there may be hundreds more yet to be discovered.

It's hard to comprehend that something as huge as the ocean can be fragile. But today, some marine species have been driven to the edge of extinction by overfishing and hunting. Global climate change threatens fragile ocean ecosystems. Development encroaches on our coastlines. And pollution stretches from shore to shore.

How can we protect the ocean? We need to understand more about it and its inhabitants—and work together to manage human impact. The key to safeguarding the ocean for the future lies with all of us.

Use the navigation at the top and right side of this site to find out more about marine ecosystems, explore the Milstein Hall of Ocean Life's dioramas, or to learn about some of the ways life in water is different from life on land.