He knew better than to tire himself out by desperate strokes.

His only hope of getting there and getting back was to conserve his strength.

All sorts of thoughts came and went in a strange jumble.
Sometimes it seemed that he was making no progress, that the slow waves were bearing him remorselessly back to the cove, or, at least just defeating the strokes of his arms and legs.

Breathing became laboured and once a veritable panic seized him and it was all he could do to keep from turning and swimming wildly back toward shore.

Instead, though, fighting his fears, he turned on his back for a moment with his round face to the blue breeze-swept sky, and took long, grateful breaths of the sun-sweet air.