I've done some spearfishing -- using conventional elastic/tubing spearguns, as well as the Hawaiian sling type. The latter is pretty simple to
construct. I would guess that local laws and Marine Regulations are what curtail much of their use. I think you're bringing this up in relation
to a Sit X or other survival situation, and in that case, perhaps the laws and regulations cease to matter, or matter less than acquiring food.
One thing that is advantageous about the snorkle/mask method is that you don't have nearly as much as a diffraction of the image when you're in the
water with your target, as you do when trying to strike into the water while standing. I'm not saying that very well. When I was a kid, we would
spear fish while standing in shallow, slow-moving places of the river. You have to aim beneath where you perceive the fish to be, because of the
diffration of light makes the fish both appear closer to the surface than it is, but also a farther angle away than it is.
When you are viewing underwater with the fish, things can appear larger than they are, but the relative line of sight from your eyes to the target is
This is also the manner in which we take lobster (in season) here, except that we are required to use a ten-foot wooden pole spear with no more than
two prongs. I like to use short, very flexible fins for manuverabity, and the only time I use long-bladed stiff fins is when freediving for conch.
If you're snorkling and on the surface for the most part, the stiffer fins can tweak your ankles a bit.
I'm not certain about your area, but here the best hunting is at night, with a light, called "torching". Many fish and crustaceans are night
hunters, and also come into shallower water. How do you do this in a survival situation with the scarcity of batteries? I have two lightweight
waterproof headlamps that are powered by three AAA rechargeable batteries. They cost about $20.00 as I recall (the headlights) and couple that with
a $16.00 solar battery recharger and extra rechargeable batteries, and a person has a lighting system that will last a good long time.
In making a sling or kinetic-energy spear, you can use surgical tubing, thinly sliced innertubes, etc. Here's one example of the H-sling type:
Good thread Agent_T..... good stuff to figure out and find about about before we NEED it.