St George explaining Nautilus’ powers

“Barry pointed out why you’re so tough,” he said to the merman. “When you’re like this, your body’s designed to survive deep underwater. Tougher, stronger, more resilient. That’s why you’re so strong on the surface.”
…
“But it hit me a few minutes ago,” said St. George, “that if you’re built for those super-high undersea pressures, really low pressure must be brutal on you. Like those stories about deep-sea fish that explode when you bring them to the surface.”
His breath, always hot from his fires, steamed in the cold air. It bit through his jacket and his wet suit and nipped at his ears and nose. He looked down and guessed the ocean was almost three miles below them.
He ****ed in a mouthful of thin air and went even higher.
Nautilus threw his elbow at St. George’s head again. It didn’t come anywhere close. The veins bulged on the arm.

Excerpt From Ex-Isle, pg 641-642
Peter Clines
https://books.apple.com/us/book/ex-isle/id989619017