Oceans cover two-thirds of the earth's surface. And while their surfaces often look smooth, the oceans are teeming with life. Oceans provide animal habitat all the way down to the ocean floor. Since oceans are, on average, over 2.5 miles deep, this means that they contain 99.5 percent of our planet's livable habitat. Within that vast space, the oceans are filled with a huge range of microscopic organisms, animals, and plant life.
If you major in marine biology, you’ll learn how this life thrives in the oceans. You’ll study such subjects as the chemical makeup of water, the ocean’s geology, marine mammals, fish, plants, and biological habitats.