What do underwater objects appear distorted when you see them from above

Because light is refracted as it passes through the air/water interface

Since air has an index of refraction of essentially 1 and water has an index of refraction of 1.33 the angle from which the rays of light reach your eyes is larger than the angle they would in air. This makes the angular size larger to your eyes which makes the object look larger relative to how they would look in air.