A sperm whale's hunting dive can plunge two kilometers into the dark

The sperm whale is the deepest-diving air-breather on Earth, and its working day looks like science fiction. Hunting dives routinely pass 1,000 meters, and the deepest recorded plunges reach roughly 2,000 meters or more — well into a zone where sunlight has long since failed and the pressure would crush a submarine’s hull.

It does all this on one breath. A foraging dive commonly lasts around 45 minutes, and individuals have stayed under for well over an hour before surfacing to recover. Down there it hunts in total darkness, including the elusive giant squid; the round suction-cup scars on many whales’ heads are souvenirs of those battles.

With no light, the whale hunts by sound. It produces sharp echolocation clicks through the huge spermaceti organ in its blunt forehead, then reads the echoes to map prey in the black water.

Those clicks are the loudest sound any animal makes — recorded at up to 236 decibels underwater.

That is louder, in its medium, than a jet engine at takeoff. Guinness World Records lists the sperm whale’s click as the loudest animal sound on the planet. A body the size of a school bus, diving past the reach of sunlight, navigating a pitch-black hunt with nothing but its own thunderous voice.