"Oshinaw Lake (not Deep Lake)" identified in the 1930 BC Gazetteer. Oshinaw Lake confirmed 8 July 1948 on 92F/6.
Source: BC place name cards, or correspondence to/from BC's Chief Geographer or BC Geographical Names Office
Local Indian name has appeared on maps since c1923; may be from "oshinoweth" meaning "all kinds of game."
According to Alberni District Historical Society, 1988, "oshinow" means "deep", which is also an established local name for the lake.