If you jumped into the water and opened your eyes everything would look blurry. That is because our eyes focus best in air, and not water. Since we are terrestrial animals this is not a problem. If we need to see underwater we can wear goggles or a diving mask. Goggles and masks help us see underwater by creating a little pocket of air in front of our eyes in addition to protecting our eyes from salt water or stinging chlorine.
No goggles needed for this African penguin.
But people? Goggles or a dive mask come in handy for seeing underwater.
Photo on left via Wikimedia Commons, photo on right is a diver in the GOT
Penguins are visual ocean hunters so they need to be able to see well underwater in order to catch fish and avoid predators. But they also need to see well on land so that they can find proper breeding sites and protect and care for their eggs and young. If a penguins' eyes could focus only in air then they would be at a disadvantage when in the water, and vice versa.
Penguins have evolved a flattened cornea which refracts light less strongly then ours and strong eye muscles that can change the shape of the lens allowing for sharper vision underwater. These adaptations allow focus in air and in water!!!
This rockhopper penguin can see well underwater and on land!
In addition, penguins have a clear eyelid called a nictitating membrane that protects their eyes when underwater.
These adaptations eliminate the need for penguins to pack goggles whenever they go to the beach.
Penguins have evolved many other amazing adaptations. The Penguin Blog is the place to learn about penguin ears and penguin knees. You can even see what scientists think prehistoric penguins looked like!