There are underwater waterfalls caused by differences in water density.

The Portuguese man o' war's tentacles can extend up to 50 meters and remain dangerous even when detached.

Some fish can breathe air in certain conditions.

The Earth's oceans regulate global temperatures.

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

Dolphins have been observed surfing ocean waves purely for fun — one of the clearest signs of play in non-human animals.

The ocean is, on average, 3,682 meters deep — the deepest point is about 11,000 meters.

The anglerfish uses a bioluminescent lure to attract prey in the dark ocean depths.

Marine iguanas in the Galapagos are the only ocean-going lizards in the world.