St George is a strong swimmer

St. George thrashed in the water, trying to get his bearings. The same dim blue-green stretched in every direction. There were no shafts of sunlight or a mirror-like surface.
Bubbles. Follow the bubbles. Bubbles go up.
He tried to relax and his lungs gave him a burning reminder he needed to get back to the surface. A few precious grams of silver air flew from his lips. They went off to the side of his mouth and raced away to his left.
Left was up.
He twisted himself around and swept his arms through the water. A few strong strokes carried him up enough that he saw daylight in the distance.

Excerpt From Ex-Isle, pg 336
Peter Clines
https://books.apple.com/us/book/ex-isle/id989619017