A possible bane to the undead, often prominent in folklore. As with witches, the vampire is unable to swim or to cross running water, as water acts as a purifier, washing away evil and sin. In Greece, troublesome revenants were “exiled” to small uninhabited islands (surrounded by water), thus isolating them and keeping them from their sources of nourishment. In some regions, the soul was thought to be thirsty so offerings of water were placed near graves to keep the deceased from wandering in search of it. A trial by water, called the iudicium aquae, was sometimes used to see if a corpse had joined the ranks of the undead: if a body floated, it was a vampire. Out of such bizarre folk traditions came the belief that running water destroys a vampire or at least renders it paralyzed. In Dracula, A.D. 1972 (1972), the vampire Johnny Alucard is destroyed by falling into a bathtub, accidentally turning on the shower. This is one of the most unique vampire exterminations in film. In Dracula—Prince of Darkness ( 1965), Count Dracula is trapped and imprisoned beneath the ice in a frozen stream until accidentally released in Dracula Has Risen from the Grave (1968).