Final answer:
The image of an object in water appears closer than it actually is due to refraction of light when passing from air to water.
Step-by-step explanation:
The image of an object in water appears closer than it actually is due to the phenomenon of refraction of light. Refraction occurs when light passes from one medium to another with a different optical density, such as from air to water. When light enters water, it bends towards the normal. This bending causes the light rays from the object to converge at a shallower depth than the actual position of the object, creating the illusion that the image is closer to the observer.
For example, if you look at a straight rod partially submerged in water, it would appear to bend at the surface. The image of the rod inside the water is formed closer to the surface, not lining up with the part of the rod above the water. This phenomenon also explains why a fish in water appears to be closer to the surface than it actually is.