Spear fishing is a great time and always a hoot to have a few divers on board during a trip.
I was first introduced into spear fishing when taking a friend of my cousin out on the boat who happened to bring his dive gear and spear guns.
Most of the time this nut just free dove down and would come up with Nice fish, I do not think I could hold my breath as long as he did though. Tanks stayed stowed in the cabin.