All underwater photgraphers love frogfish. We can't help ourselves. They're just so obliging sitting there convinced you can't see past their camouflage as you shoot away. But more than that they look so cool. This is an absolutely huge Commerson's frogfish. Check out his "foot" in bottom left. You'd think that having chosen a shade of acid yellow he'd be pretty easy to spot.
but switching slightly wider you can see he does a pretty good job of blending in.
Froggies have a sensationally fast-moving collapsable jaw structure so that if you watch one long enough you may see a fish swimming past seem to disappear as the froggie swallows it faster than the human eye can follow.