At the far end of the pond, the water approaches the reflectivity of a perfect mirror because we’re looking straight across it at a very shallow angle. At shallow angles, most of the light bounces off the water (reflection) rather than angling down into it (refraction.)
At steep angles of view, the opposite happens: we see less reflection and more refraction. Therefore the water is dark and we see the fish more than the sky or the trees.
Wikipedia about "Three Worlds"
Color and Light, page 200.
Previously on GurneyJourney: Transparency of Water
