Lake Afrera (also transliterated as Lake Afdera) is a hypersaline lake in northern Ethiopia. Located in Administrative Zone 2 of the Afar Region, it is one of the lakes of the Danakil Depression. According to its entry in Lakenet, it has a surface area of 100 km2 (39 sq mi), although another source states the area is 125 km2 (48 sq mi). An unconfirmed report gives its depth as 160 m (525 ft); the lake is fed by underground streams.
It is also known as Lake Giulietti, the name Raimondo Franchetti bequeathed it, after the Italian explorer Giuseppe Maria Giulietti who was slain by Afars southwest of the lake. Another name for this body of water is Lake Egogi (or Egogi Bad), which is the name L. M. Nesbitt's Afar guide gave it when the Italian explorer became the first European to see it in 1928.
The single island in Lake Afrera, Franchetti Island (also known as "Deset"), located in the southern part of the lake, is considered the lowest-lying island in the world.
Unlike other saline lakes in Ethiopia (e.g., Lakes Abijatta, Shala, and Chitu), the pH of Lake Afrera is low and in the acidic range. Although little studied, a few species of fish are hosted by Lake Afrera, including two endemics: Danakilia franchettii (a cichlid) and Aphanius stiassnyae (syn. Lebias stiassnyae; a pupfish).