Sumela Monastery (Μονή Παναγίας Σουμελά, Moní Panagías Soumelá; Sümela Manastırı, სუმელა) is a Greek Orthodox monastery dedicated to the Theotokos located at Karadağ (Greek: Sou Melá, meaning "Black Mountain") within the Pontic Mountains, in the Maçka district of Trabzon Province in modern Turkey.
Nestled in a steep cliff at an altitude of about facing the Altındere valley, it is a site of great historical and cultural significance, as well as a major tourist attraction within Altındere National Park. Due to an increase in rock falls, on 22 September 2015 the monastery was closed to the public for safety reasons for the duration of one year to resolve the problem; this was later extended to three years. It reopened to tourists 25 May 2019. The monastery is one of the most important historic and touristic venues in Trabzon.
Soumela comes from the Greek 'Sou Melá', meaning "of black (mountain)" (as in the dark/black mountain).
According to another etymological theory regarding the origin of the monastery's name, it comes from the Laz word სუმელა [sumela], which means "Trinity" in English.
It is not known when the monastery was founded, but the Turkish Ministry of Culture and Tourism places the date around AD 386, during the reign of the emperor Theodosius I (375–395). According to William Miller, two Athenian monks named Barnabas and Sophronios founded the monastery. It became famous for an icon of the Theotokos known as the Panagia Gorgoepekoos, said to have been painted by the Apostle Luke.
During its long history, the monastery fell into ruin several times and was restored by various emperors. During the 6th century, it was restored and enlarged by the Byzantine general Belisarius at the behest of emperor Justinian.
It reached its present form in the 13th century after gaining prominence during the existence of the Empire of Trebizond. While the emperors Basil and John II had endowed the monastery richly, it was during the reign of Alexios III (1349–1390) that Sumela received its most important largess: according to legend, the young Alexios was saved from a storm by the Theotokos, and was bidden by her to restore the monastery.