Things look shallower under water

A coin at the bottom of a basin of water looks a little higher than it really is.

The light from the coin comes up through the water and bends away from the normal as it leaves the surface. Traced back, the rays reaching your eye seem to come from a point above the coin, so the coin appears raised: its apparent depth is less than its real depth.

Letters seen through a glass block laid on a page look raised for the same reason.