The deep ocean is home to brine pools — underwater lakes of super-salty water that are toxic to most marine life.

The Arctic Ocean is the smallest ocean.

The giant squid lives in deep ocean waters.

The ocean contains structures larger than mountain ranges.

The Mediterranean Sea loses more water to evaporation than it gains from rivers, maintained by inflow from the Atlantic.

Deep-sea fish like the barreleye have transparent heads and tubular eyes that can rotate to face upward.

Greenland's ice sheet is melting at accelerating rates, contributing significantly to global sea-level rise.

Dolphins surf ocean waves purely for fun — one of the clearest signs of play behavior in animals.

Some species of nudibranch (sea slug) incorporate stinging cells from jellyfish into their own bodies for defense.