Effects of Water Density on Light
![refraction of light underwater](images/light-refraction.jpg)
Water and Refraction of Light
As light passes from air to water, its speed slows down and the light rays are bent. This is called "refraction," and affects the appearance of everything you see underwater.
Refraction causes objects to appear 33% larger and closer. You can see this effect by placing a straw in a glass of water. The straw appears to break at the surface of the water because the portion in the water appears closer and larger than the portion above the water.
Divers must consider the effects of refraction when judging distances and the size of marine life. Objects that appear to be within reach are actually farther, and those fish that appear massive are actually much smaller.
Refraction causes objects to appear 33% larger and closer. You can see this effect by placing a straw in a glass of water. The straw appears to break at the surface of the water because the portion in the water appears closer and larger than the portion above the water.
Divers must consider the effects of refraction when judging distances and the size of marine life. Objects that appear to be within reach are actually farther, and those fish that appear massive are actually much smaller.