system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it that I can't see clearly under water without swimming goggles?
gpt
Your eyes have evolved to see in air, your corneas have evolved to shape and focus light passing from air into the eye. The different refractive index of water makes it so that your cornea focuses the image in the wrong spot. Goggles/masks give an air gap that allow the image to form properly. However, the refractive change from the water, through the lens, into the air, makes things look bigger than they are, that shark you saw diving wasn't 12 feet long, it was more like 9.