The fish’s-eye view
At whatever depth a fish happens to be it has a full view of everything above the water, provided, of course, that the water surface is unruffled. Fig. 23.13 explains this and shows how the fish enjoys a 1800 field of view apparently all squeezed into a cone of angle about 980 (i.e., twice the critical angle for water). Outside this range the fish will see objects in the water and on the bottom which are mirrored in the surface of the water by total internal reflection.