 Like a pole spear, the diver must exert force on the shaft to keep it from releasing, whereas a spear gun has a trigger mechanism to accomplish this.The modern Hawaiian sling was popularised in the mid 1950s; however, fishing slings are mentioned in anthropological journals as early as 1917.In some parts of the world, in order to limit the catch, the Hawaiian Sling is the only type of spearfishing gear permissible.