Nettilling Lake [nech'iling] is a cold freshwater lake located toward the south end of Baffin Island, Nunavut, Canada. It is also the world's largest lake on an island, with an area of 5,542 km² and a maximum length of 123 km. The lake is in the Great Plain of the Koukdjuak about 280 km 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).