Lake Tana is Ethiopia’s largest lake and a major source of the Blue Nile.
The lake lies in the north-western Ethiopian Highlands in the Amhara Region, at an elevation of about 1,788 metres. It is fed by rivers including the Gilgel Abay, Gumara, Reb and Megech, and its outflow becomes the Blue Nile, known locally as the Abbay. The river continues toward Sudan, where it joins the White Nile at Khartoum.
Lake Tana is roughly 84 kilometres long and 66 kilometres wide, but comparatively shallow, with a maximum depth of about 15 metres. Its surface area changes seasonally with rainfall and inflow. A control weir regulates discharge toward the Blue Nile Falls and downstream hydropower facilities.
The lake is also culturally important. Islands and peninsulas contain historic Ethiopian Orthodox monasteries, some dating to the medieval period. Its fish community includes many endemic species, especially distinctive Labeobarbus barbs. The nearby Lake Tana region was designated a UNESCO Biosphere Reserve in 2015.