Simian Island is an island on the Danube, located downstream of the Iron Gates I hydropower plant, between Romania and Serbia, to the south-east of the municipality of Drobeta Turnu-Severin, near Simian in Mehedinti County. The island has an area of 55.50 hectares. As a territorial-administrative classification it belongs to the commune Simian.

Archaeological findings show that the island has been inhabited since the Middle Neolithic, finding traces of the Starcevo-Cri? and Turdas-Vinca cultures. In 1968, before the construction of the Iron Gates Reservoir, the sights on the island of Ada Kaleh were moved to Simian Island, objectives still on the territory of the island, but in a state of degradation.