Lake Tana is Ethiopia’s largest lake by surface area and the source of the Blue Nile.
The lake lies in the Ethiopian Highlands at an elevation of about 1,786 metres. Its area varies with seasonal rainfall, but it generally covers roughly 3,000 to 3,600 square kilometres. Several major rivers, including the Gilgel Abay, feed the lake.
The Blue Nile begins at Lake Tana’s southeastern outlet and flows toward Sudan before joining the White Nile at Khartoum. The Blue Nile is a major tributary of the Nile, although the White Nile contributes more of the Nile’s flow near the confluence during some seasons.
Lake Tana also has historic island and lakeshore monasteries, many dating from medieval Ethiopia. The lake supports important fisheries and wetland habitats, while its outlet is controlled near the Chara Chara Weir for water management and hydropower.