First, they're one of the few birds that can't fly.

For one thing, they are one of the few bird species that cannot fly, having evolved from flight-capable birds about 60 million years ago. Surprisingly, their closest living relative is the albatross, a bird known for its enormous wingspan and extraordinary soaring abilities. It may seem strange that losing the ability to fly would be an evolutionary advantage, but the penguin's short, flipper-like wings and solid bones allow them to swim faster and dive deeper than any other bird on Earth, filling an ecological niche that no other bird can. Penguins inhabit the southern hemisphere, being one of the few bird species able to breed in the coldest environments.