How do penguins blend in with their environment?

Penguins are not one of the best examples of camouflage when they are on the ice in Antarctica. That is because their black back gives them away against the white ice.

However, that tuxedo coloration is useful underwater. This is because an animal underneath a penguin would have difficulty seeing its underbelly against the light coming from the surface. From above the penguin, its dark back blends in with the dark depths of the ocean.