Question: why are fish able to go to the bottom of the ocean but we can not

Ciarán O'Brien answered on 18 Nov 2014:

Fish are adapted to living in water, while we’re adapted to living in the open air. We have a lot of thin fragile membranes easily damaged by pressure, like ear drums and eyeballs, whereas fish don’t have ears and their eyes are much tougher.

Fish also have way less air in their bodies. They don’t have lungs, and most of the empty space in their bodies is filled with water. They have a little air sac they use to control whether they sink, rise, or flot in the same place, but it’s also tougher than our lungs. Water is very hard to compress, but air is easy to compress. So fish are affected less by the increasing pressure as you head further below the water than humans are.

All that said, fish have to be very careful about pressure too. Fish don’t like to go too deep or even too shallow! If they go to the bottom of the ocean too quickly that’ll damage them. And if they come back up too quickly they actually explode because the pressure decreases so fast!