Penguins are birds that have adapted to the sea, so they're great swimmers. But on land they walk clumsily and they can't get up into the air at all. Penguins do have wings but they're short and thick-useless for swimming. Penguins also use their wings to signal their friends and to scare away enemies. So, when you see penguins flapping their wings together quickly, don't think they're trying to fly.