The ocean has killed more billionaires than the Moon has.

Whales suffocate to death; they don’t drown.

Human breathing is controlled by the autonomic nervous system. We have to hold our breath on purpose to stop ourselves from automatically breathing. This makes us passive breathers. Whales, however, are active breathers. They must choose to inhale which is why they can sleep without sucking in air. When they get too old, sick, or weak to surface, they suffocate.

Bonus fact: whales can’t breathe through their mouths; it goes straight to the stomach. The blowhole is the only respiratory tract.

Bonus bonus: a blue whale’s throat is so small it could choke to death on a grapefruit.

The Blue Whale is so large, that if you laid one out on a standard NBA basketball court, the game would be postponed.

Billy Ocean has an honorary doctorate of music from the University of Westminster.

Did you know fish fuck in the ocean? Remember that, when you go for a swim.

Lobsters have urine nozzles under their eyes, and pee in each other’s faces to communicate.

When a whale dies and its corpse falls to the bottom of the ocean, entire ecosystems rapidly develop around eating every part of it due to how scarce resources are in the deep ocean. This phenomenon is called a "whale fall" and it's a major source of energy for deep ocean ecosystems.

There are lakes in the ocean called brine lakes/pools. Brine is essentially concentrated saltwater; its high salinity means it's denser than water. On rare occasions, brine doesn't mix enough with the existing saltwater around it, sinking to the bottom of the ocean and forming these lakes. The lake itself is usually devoid of life; brine itself is so salty that animals go into toxic shock if exposed for too long. However, the edges usually are full of life, where usually things like mussels and other extremophile organisms thrive.

Side note, subnautica's lost river is based off of this. No big leviathans in real life though, at least none observed yet...

Video for fun: https://youtu.be/ZwuVpNYrKPY

There are entire levels of the ocean where ecosystem is fed on the slow sinking of dying animals.