Nothing. But in the last two years, yesterday was the third time I've had to stop bleeding on someone else while in the water. In this case, I used my Shelta face gaiter as a pressure bandage, and bound the injury on her foot tight enough that we got it stopped. Only 500 meters off shore, but through current and chop, that's sure a long way when you have a gusher, you're scared, and the BP is up due to the effort required. I carry a pretty extensive med kit in my van...but it's in my van. Once on shore, got her patched up good enough to be driven to the hospital.
Part of my kit is a SWAT-T tourniquet. Pretty small, and last night I was thinking that I might start carrying it out in the water. There's not a lot of surfing-related injuries where it's feasible to carry the kit to address the issue in the water. Head injuries, breaks, dislocations...all stuff that the victim needs to be brought to shore to start really dealing with it, and although painful, most aren't severely time-sensitive. But bleeding! That's a serious one that may need to be dealt with immediately in order to save someone's life, and the most common issue I see, by far. The rubber-band style tourniquets are doubly useful in that they aren't just an arterial tourniquet, but work very well as a simple pressure bandage. It should go without saying, but all the kit in the world is useless without the knowledge of how to apply it. We're more likely to have to deal with someone else's injury, though, so I feel it's doubly important to know how to get someone else to shore under a whole host of circumstances. Applying a pressure dressing in rough water is way different than doing it in the parking lot.
Next, we move on to what colas is saying. Prepare yourself. Some people hate to knee or prone paddle, but in the places I surf, one should be able to. A snapped paddle is a bummer, but a lot more of a bummer when you're 1.5km off shore. Broken arm? I may not practice a one-arm side stroke for that distance on the regular, but I'm confident in my ability to do it. Know how to paddle swim if the board is lost, and on and on.
Last, but probably the largest "piece of kit" that goes towards keeping us out of trouble, is risk assessment. I surf by myself a lot, or just myself and one other person. Always reef. Often far from shore, or far from the closest take-out point. I choose a peak that's well within my comfort zone, don't take the risks I did when I was 20, and you'll usually find me wearing a helmet and impact/float vest
