Spearfisherman was a company that made dry suits and swimfins (and perhaps other types of underwater diving gear). Located in Huntington Beach, California, Arthur Brown started it in or before 1945 and sold it to Swimaster about 1955, which, in turn, was sold to the Voit Rubber Company in the early 1960s.
Swimaster was one of the five original United States diving gear makers: U.S. Divers, Healthways, Voit, Dacor, Swimaster.