Spear fishing has been practised for centuries. American Indians used spears that had copper or bone points attached to wooden shafts for large fish and a trident, or three-pronged spear head on a wooden shaft for small fish.
A pole spear is similar to the original spear used by the native American Indians in that it has a long shaft with a point on the end. However, on the other end is a loop made of elastic. The elastic band is how you propel or throw the spear, in a similar fashion to the Paleoindian spear thrower. The shafts of the spear can be wood, fibreglass, titanium, aluminium or carbon fibre.
The Hawaiian sling is similar to the pole spear in that it consists of a long shaft. To actuate the Hawaiian sling, fire it off the weapon in a manner similar to a bow and arrow. Another difference from the pole spear is that it has no string attached to it so that you could lose your spear after you fire it.
The spear gun looks like a rifle---except that it fires spears. The spears often have long strings attached to them so you don't lose the spear or the fish you shoot. These spear guns are powered by elastic bands, pneumatically, explosive cartridge as well as gas. Some of these spear guns have a reel, similar to a fishing rod, by which you retrieve your spear after you fire it.