Penguins are some of the world’s most popular birds: their stout bodies, striking coloring, and endearing waddling gaits make them easy to love. But they’re not just cute to look at—they’re incredibly well-adapted to life in icy water.

Penguins might look awkward on land, but their fat helps keep them warm, and their streamlined bodies allow them to cut through water with surprising speed and grace. Penguins can reach speeds of up to 25 miles per hour swimming.

Even penguins’ coloring helps them survive in the water. They’re counter-shaded, meaning that their backs are black and their bellies are white. On land, that makes them stand out, but when they’re swimming underwater, it helps them blend in. From underneath, a swimming penguin’s white belly blends in with the light streaming from the sky. From above, a penguin’s dark back camouflages with the dark ocean below!

Photo by Ken Funakoshi