I was building a boat on the water at night when I noticed a skeleton walking in the water. It got out and went in again, got out, and went in again. It repeated this until morning. At morning, it got out, nearly burned to death, and went back to the water and stayed there. It did not drown. I was in Creative Mode. My seed is 6963544522046458314.
Skeletons do not start drowning instantly, and burning mobs automatically pathfind into water.