Gents Hamilton Black Khaki FrogmanHamiltons 300m water resistant diver got its name from the US Navy combat divers who wore the original tool watch during WWII. Although most of us associate Hamilton with its robust pilot and field watches, Hamilton got real life experience in waterproof watches from a model used by US Navy underwater demolitions teams. Dating back to 1943, Hamiltons diver with an unusual locking mechanism on the crown was part of the Naval Combat Demolition Units