What causes objects to appear larger and closer when viewed underwater?

Objects appear larger and closer when viewed underwater primarily due to the refraction of light. Refraction occurs when light passes from one medium to another, in this case, from air to water. As light travels from a denser medium (water) into a less dense medium (air), it bends. This bending magnifies the size of objects and creates the illusion that they are closer than they actually are.

For example, if you're submerged in water and look at an object, such as a fish or a rock on the lakebed, the light rays coming from that object change direction as they cross the water's surface into your eyes. The bending effect can significantly alter your perception of distance and size. This is why underwater photographs or observations often depict objects as being larger and closer than their true dimensions.

Absorption of light refers to the loss of certain wavelengths of light as they pass through water, which affects visibility and color but does not influence the perceived size and distance of objects. Diffusion of light involves the scattering of light waves, which contributes to the overall visibility but does not cause the apparent enlargement of objects. Reflection of light occurs when light bounces off surfaces, affecting how we perceive objects, but again, does not contribute to the magnification