This activity quantifies an experience many students have had visiting a beach, or even playing in a sandbox. A summer afternoon walk, barefoot, across sand can burn one's feet. Often people take a few steps and then bury their feet in the cooler subsurface sand as they make their way across the beach. After sunset, the surface sand cools rapidly and buried feet are warmed by the deeper sand that has not cooled off yet. Stopping to rest on an empty fire ring, the beach walker notices how warm the concrete ring is long after the Sun has gone down.