A long day swimming at a pool or the beach typically wraps up with a hungry belly, hopefully sunburn-free skin, and wrinkly fingers. It is also the skin that wrinkles when exposed to water for a long time. [ Related: Why do our fingers wrinkle in water? “Blood vessels don’t change their position much–they move around a bit, but in relation to other blood vessels, they’re pretty static,” German said in a statement. “We’ve heard that wrinkles don’t form in people who have median nerve damage in their fingers,” German said.