Question

a technical diver takes a dive to 55 meters deep where they encounter a yellow fish. what color will the fish appear to be to the diver?

Explanation:

When light travels through water, it gets absorbed. Red light has the longest wavelength among the visible spectrum and is absorbed first as depth increases. Yellow light is a combination of red and green light. At 55 meters, the red component is mostly absorbed. Green light has a shorter wavelength than red and can penetrate deeper. But when we consider the color perception, blue light (shorter - wavelength) can still be present and interact with the fish. Since yellow (red + green) loses its red part (absorbed), and if we consider the remaining light - interaction and the fact that blue light can still be there (as it has a shorter wavelength and is absorbed less quickly than red in water), the fish will appear blue.

Answer:

blue