Psathoura is a Greek island in the Northern Sporades. It is administratively a part of Alonnisos. As of 2011, it had no resident population. The Psathoura lighthouse, built in 1895, stands at 28.9 metres. It is one of the tallest in the Aegean. Its signal is a flash of one second every ten seconds. All of Psathoura is in Zone A2 of the Alonnisos Marine Park.