Thanks for the help! I guess the most important way to avoid dying from an SWB is to always dive and train with a partner. As far as equipment goes, what do I need? So far I know I need a snorkel, mask, fins, float, and gun. I already have wetsuits and a speargun. Am I missing something? What kind of float do I need? Also I was reading that people attach their gun to a float line which is attached to the float itself. Is this necessary, and why do they do it?
I attach my speargun to my float via a polypropylene
float-line (of 12m-20m) - South African style. Mainly to avoid loosing my speargun -- but it might also allow you to avoid loosing a large fish (perhaps more of an issue with large pelagic fish abroad). A lot of folk don't though (and some loose a speargun from time to time). The line can be a hassle but I've been doing it since I started and have just got used to it.
Weight-belt and weights, mainly to offset the extra buoyancy of the wetsuit. A
fish stringer - I like the big Rob Allen ones but they'd become expensive last time I checked, fortunately the inexpensive Omer monofilament stringers work almost as well and have the advantage that you can cut them with a knife. You can use the spike of the fish stringer (or even the point of your spear) to dispatch fish - but a
spearo dagger works best (I would recommend a small one rather than a large one) - it can potentially double as your dive safety knife.
Your
float should be reasonably large and visible, and should have a diver-down flag. In North America, that's usually a red flag with a white diagonal stripe. For the most of the rest of the world, it is the blue and white "alpha"/A flag. The float is intended to keep boats away but it also acts as a place to hand your fish (on your fish stringer), you may or may not carry other items on it (e.g. compass, whistle, VHF radio, mobile phone, drinking water, crab net, crab hook, flares*), and attach your float-line/speargun - it also helps folk on shore keep track of your whereabouts. By the way, you may need to add
ballast to the bottom of the float to keep the flag upright in wind/heavy seas (e.g. old wheel lead weights, a small dive weight or some folded lead sheeting).
*I usually prefer to keep it simple & stream-line: a small
plastic whistle, a folded
crab bag, fish stringer &
2 clips (I use two old, anodized aluminium Clogg Wales climbing karabiners - but there are various plastic/brass/stainless-steel alternatives) for fast, secure attachment.