Penguins are some of the coolest birds in the world, and one of my favorites. They're the only bird on Earth that traded the sky for the sea.

Unlike other birds, penguins don't have wings with long feathers that enable them to fly in the air. Instead, their wings evolved into powerful flippers that help them "fly" through the water.

Penguins even have a built-in turbocharger. They blast jets of bubbles trapped in their feathers that accelerate them through the water like torpedoes.

They are covered with thousands of tiny feathers packed together so tightly that they create a waterproof layer, keeping the icy ocean away from their skin.

Most birds are lean and lightweight. But some penguins, let's just say, took a different approach. That extra junk in the trunk is the perfect insulation for their icy habitat.

Penguins can dive deeper than any other bird in the world. Some can reach depths of more than 1,800 feet. That's 5 football fields straight down!

And they can stay underwater for more than 20 minutes before needing to come up for air. I can hold my breath in the pool for a minute and a half. That's pretty close, right?

Most penguins are expert fish hunters. They dart and dive to catch fish, krill, and squid. Their sharp eyesight and speedy flippers make them the underwater ninjas of the ocean.

But penguins have to watch out for their own predators. Seals and orcas hunt them.

On land, they have to constantly be on the look out for sneaky birds trying to snatch their eggs and chicks.

Just like dolphins, penguins often leap in and out of the water as they swim. This swimming technique is called porpoising. It helps them travel faster and grab quick breaths of air along the way.

To get back on land, penguins launch themselves out of the water like rockets.

On land, penguins often slide across the ice on their bellies. That's called tobogganing. It's faster than waddling and uses less energy.

Penguins can drink seawater. They get rid of extra salt by "crying" it out from special glands above their eyes. I wish we could do that so swallowing a mouthful of ocean water at the beach wouldn't taste so gross.

There are 18 species of penguins alive today. The largest is the emperor penguin, standing about 4 feet tall.

The smallest, and definitely the cutest, is called the Little Penguin. They're only about 12 inches tall and weigh only 2 pounds. So adorable!

Penguins have been around for millions of years. Some ancient, extinct penguins were giants. They stood nearly 7 feet tall and weighed as much as 200 pounds!

I always thought of penguins as living in cold places, like Antarctica. But penguins actually live in many different habitats around the world.

Some penguin species live in temperate climates with thick forests.

And some even live on hot tropical beaches and islands along the equator.

Each species has its own special way of keeping its eggs and chicks safe. Some build nests from pebbles, some dig burrows underground, and others hide their eggs in caves or forests.

Emperor penguins balance their eggs on their feet and cover them with a fold of skin to keep them warm for two months straight. Now that's the kind of patience I definitely don't have.

One thing that's pretty gross is the way penguin chicks eat. Since they can't swim and catch their own food yet, penguin parents regurgitate (that's vomit) their food for the chicks to eat.

Penguins may not be able to fly. But by trading the sky for the sea, they became some of the most amazing birds on Earth. And honestly, I think that's a pretty good trade.