The Sea Lions were "floating" in the water while taking a nap. This is one of several that were grouped together by the observation tunnel. Their bodies would rise and fall, twist and turn. Kind of spooky and surreal. What made it crazier is that the Harbor Seals would swim through the Sea Lions, almost as if they were trying to wake them up!

St Louis Zoo, Sea Lion Sound observation tunnel.

Nikon D800 with Nikkor VR 28-300mm f/3.5-5.6G
@28mm, f/4.5, 1/125s, ISO 560, converted to B&W