It was a different world then! This LIFE Magazine pictorial from July 18, 1938 is titled "Men Now Bathe Without Tops On Many Public Beaches":

In Europe and on the West Coast topless bathing for men has long been no novelty on public as well as private beaches. But in the more inhibited East a male costume consisting solely of trunks was, until just recently, cause for arrest on almost all public beaches and raised eyebrows on many a private one.

At Atlantic City topless bathing suits are still forbidden, and only this year has Long Island's ultrademocratic Long Beach allowed men to air their backs and chests. This trend which originated on the French Riviera has seriously distressed manufacturers who claim there is little field for originality of design in trunks. For proof of their contention, see Long Beach pictures below.