St George can high dive, Nautilus’ strength explained

“If I build up enough speed,” said St. George, “I might be able to grab him and drag him out.”
What do you mean?
“Straight up, straight down. A high dive.”
Devon frowned. “Won’t that just, like, crush you?”
“I’m tougher than I look.”
“He’s going to have home court advantage,” said Zzzap. “Better sight, better maneuverability. A chunk of your strength is just going to go to fighting water pressure.”
“Yeah, but so will his.”
“No,” said the gleaming wraith, “his body’s designed around being underwater. That’s why he’s so strong on the surface.”

Excerpt From Ex-Isle, pg 529
Peter Clines
https://books.apple.com/us/book/ex-isle/id989619017