Set at an altitude of 1,750 m, Lake Tana is the largest lake in Ethiopia, with a surface area of 3,673 km2. It is also the source of the Blue Nile River, a connection that explains many of Ethiopia's links with the world. Tana was known to the ancient Greeks as Pseboe, and to the ancient Egyptians as Coloe; it was described by a 5th century Greek dramatist as the "copper-tinted lake ... that is the jewel of Ethiopia".
There are 37 islands that are scattered about the surface of Lake Tana, out of which 21 shelter churches and monasteries of immense historical and cultural interest. These churches are decorated with beautiful paintings and house innumerable treasures. Their location may have saved them from looters.