A whale skeleton. A “Jaws” poster. A sneakbox loaded with hand-carved decoys. Original Tuckerton Railroad tickets behind glass. A dugout canoe found on a Beach Haven jetty in 2006, carbon-dated to between 140 and 410 AD. This is the Long Beach Island Historical Museum: 50 years old, entirely volunteer-run and, as it turns out, almost never built.

The Long Beach Island Historical Association marked the anniversary milestone May 30 with guided and self-guided tours, a 50-year timeline exhibit and…