How deep-sea fish survive pressure that crushes subs.

Added: 2026-06-04

[00:00:00]The subs that reach the bottom of the ocean used a titanium sphere nearly 4 in thick. Anything thinner implodes. Yet, a fish the size of your hand lives 5 mi down with no shell at all.

[00:00:14]>> [music] >> It isn't stronger than the sub. It does the opposite.

[00:00:19]Down there, [music] the water presses 800 times harder than at sea level.

[00:00:24]A submarine survives by sealing a pocket of air and bracing against all of it.

[00:00:30]That gap, [music] calm inside, crushing outside, is what implodes a hole.

[00:00:36]The fish carries no such gap. It's mostly [music] water, and water barely compresses. Inside, the pressure is exactly as high as outside. Nothing to push [music] against. Nothing to break.

[00:00:50]It doesn't resist the ocean. It lets the ocean in.

[00:00:55]But, pressure still attacks the proteins inside, prying them open until [music] they stop working.

[00:01:02]So, its cells are flooded with a molecule called >> [music] >> TMAO.

[00:01:06]It reorders the water around each protein and holds it folded. A chemical brace instead of a steel one.

[00:01:14]The deeper a fish [music] lives, the more of it it carries. Past 5 mi, it would need so much TMAO that its body turns as salty as the sea itself.

[00:01:25]No fish has ever been found below about 8 and 1/2 km.

[00:01:30]Not because the pressure wins, because the chemistry runs out first.

[00:01:35]Below that line, the deep belongs to things without a spine.