Nettilling Lake is a cold freshwater lake located toward the south end of Baffin Island in the Qikiqtaaluk Region, Nunavut, Canada. It is the 27th largest lake in the world by area, and the world's largest lake on an island, with an area of 5,542 km2 (2,140 sq mi) and a maximum length of 123 km (76 mi). The lake is in the Great Plain of the Koukdjuak about 280 km (170 mi) northwest of Iqaluit. The Arctic Circle crosses the lake. The lake's name is of Inuktitut origin, coming from the word for the adult ringed seal (netsilak). Franz Boas explored its southern shore in 1884.