Jacob is, unfortunately in this situation, made of dense muscle. Where Cold is lithe, Jacob is solid, broad and barrel-shaped. Bubbles escape his nose and mouth as he fights the chill weighing down his limbs, pulling on the chain until the door opens wider still. He can't risk letting too much water flood the space beyond, but he also needs to get through the damn thing, and that's going to be difficult with how sluggish and heavy he feels.

Eventually, he has to stop, not because it's enough, but because he can't hold his breath any longer. He can't stop his lungs hurting, burning, fire in his limbs fighting the cold but only making it all much worse.

He moves towards the doors, getting one arm and shoulder through, using what little resource he has left in his muscles to force himself through. The door gives just a tad more with those shoulders braced against it, water rushing in over him into the room beyond and then suddenly he's through, gasping and shivering. But he doesn't stop, doesn't collapse and splutter.

He finds some purchase, finds a grip, and forces the doors to shut a little, to slow the water ingress. It's harder to fight against the water trying to push the water in, but eventually, the gap is closed up again, to the narrow width of Cold's frame.

And then he slumps. Fights to fill his lungs with stale air, but air all the same.