One obvious preventative measure is to practice lots of stretching, not just before your race but throughout the season. Leg flexibility is relative, and triathletes are habitually less flexible than swimmers. Concentrate on ankle flexibility so that you are able to point your toes on the down-kick of your kick cycle; often, triathletes kick incorrectly with their feet at a 90 degree angle to their shins, contributing to the likelihood of a calf cramp while adding extra drag.
Potassium is known to prevent cramps. If you don't take supplements or eat bananas regularly, that could be your answer if you're known to suffer from exercise-induced cramps.
Should a cramp occur during a race, do not panic. Be aware that you are experiencing one and stop swimming. Tread water and slowly try rotating your foot at the ankle to work out the cramp (if it occurs in your calf). Oftentimes you can stop a cramp with this approach. The severe cases occur when an athlete panics and tenses up all muscles in the body, resulting in further muscle contractions and convulsions.
3. Your Swim Cap Tears or Falls Off
It may not seem like the end of the world, but to a swimmer with long hair, losing her cap is a miserable experience. In addition, a swimmer whose cap falls off usually loses her goggles too, since goggles traditionally go over the cap.
Obviously, an easy solution to this potential problem is to wear your hair short if you compete in open water. You can (and should) still wear a cap for warmth and easy identification by race officials. But the longer your hair, the more likely it is to get in your eyes (or worse, your mouth) should your cap rip or slip back on your head. A tight ponytail tied with elastic will at least keep the hair from spreading across your face if you insist on keeping it long
You might consider putting your goggles on under your cap, a unique technique favored by open-water champ Dawn Heckman. This prevents you from losing your goggles should your cap unexpectedly fall off.
I personally never like to wear a brand-new cap on race day. This is because new caps have not been stretched out by a few prior uses, and are thus more likely to slip off the first time they are worn.
Conversely, it is important not to wear a cap you have been wearing for a few weeks, as it could be stretched out to the point of being loose enough to fall off. If the race rules don't require mandatory color-coded and pre-supplied caps, choose one you have worn a few times that fits snugly but not too tight. Make sure to inspect it along the seam for tiny cracks that could turn into tears.
4. Brand-New Blisters
As devoted cross-trainers, we sometimes end up with cross-training injuries. Most common (and annoying) among these is the fresh running blister that pops open in the water, resulting in that loose bit of skin that burns and flaps every time it gets wet.
While some may hesitate to even call this an injury, anyone who has ever swum with an open blister in salt water can attest that it is excruciatingly painful, maddening and distracting.
Band-Aids are seldom effective, as they slip off within moments of entering the water (especially if you are kicking aggressively). However, a Band-Aid wrapped with waterproof tape has worked for me in the past (I've wrapped the tape around my entire foot bridge, or toe, depending on the location of the blister).