Question (Spoilers)

In the scene where the protagonist is trying to save the life of his injured brother, he swims back up to the diving bell, without a mask, just holding his breath. Could a person possibly survive the water pressure at 320 meters under water? Could the air in his lungs even withstand the pressure? How accurate is this?


__________________
If we could see ourselves as others see us, we would vanish on the spot. - E.M. Cioran