Some Antarctic fish have colorless blood.
Icefish are the only known vertebrates that live without hemoglobin—the protein that makes our blood red and carries most of its oxygen. Instead, oxygen dissolves directly in their blood plasma.
That works because Antarctic water is exceptionally cold and oxygen-rich, and icefish compensate with large hearts and high blood flow. It’s an evolutionary workaround that would fail spectacularly in warmer water.
Earth’s largest waterfall is underwater.
In the Denmark Strait, between Greenland and Iceland, cold, dense water spills beneath warmer water and plunges roughly 3,500 metres down the seafloor—more than three times the height of Angel Falls.
It’s called the Denmark Strait cataract: a waterfall made of water falling through other water.
There are “lakes” at the bottom of the ocean—with shorelines and rippling surfaces.
They’re called brine pools: pockets of water so salty and dense that they settle beneath ordinary seawater instead of readily mixing with it. Some contain so little oxygen and so much hydrogen sulfide that animals swimming into them can die, even while specialized microbes thrive nearby.