Some fish use countershading to camouflage in water.

The ocean contains structures larger than mountain ranges.

There are underwater waterfalls caused by differences in water density.

The Pacific Ocean contains thousands of islands.

The deep ocean floor is covered with fine sediment known as ooze.

Certain fish clean parasites from larger fish.

Surfer Garrett McNamara rode a 78-foot wave off Nazaré, Portugal, in 2011 — a record at the time.

Sea otters wrap themselves in kelp to stay anchored while sleeping.

Exploration of the deep sea has revealed that bioluminescence is far more common than previously thought — it may be the dominant form of communication in the ocean's depths.