Penguins are unique flightless birds that live in the Southern Hemisphere, with some species in Antarctica and others in more temperate climates. They come in a range of sizes, from the smallest Fairy Penguin to the largest Emperor Penguin. Penguins are excellent swimmers and spend most of their time in the water, propelling themselves with paddle-like wings and catching fish, squid, and krill. They come ashore only to mate and raise their young, laying eggs in nests on land and taking turns incubating them until the chicks hatch.