No logic involve! Just watch the first 10 minutes and you will see a women being drag by a shark at I don't know like 150 meters deep in the water. She is like screaming in the process (meaning there's no air left in her lungs after the dragging) miraculously she managed to survive. I feel like the director is in some kind of high grade crack thinking that swimming from 150+ meters going up without air in your lungs is manageable.