Psathoura (Greek: Ψαθούρα) is a Greekisland in the Northern Sporades. It is administratively a part of Alonnisos and forms a depopulated sub-municipal district which is not officially a settlement. 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.