Open Water Swim Starts
The start of a race can be anxiety-inducing. You're nervous. Excited. Ready to go. But often times the start of a triathlon or open water swim is going to be very different than what you do in training. Below is some very general info on how open water swims start, some drills you can do in the pool to prepare, and basic guidelines to help you have an efficient, controlled start to your race.
The Start
Mass Start
A mass start is exactly what it sounds like -- a gun goes off and everyone begins at the same time. This often involves getting kicked, punched, grabbed, and swam over, and for individuals who are not that comfortable in the water (and often for those that are) swimming in a large group like this can be a lot. It can feel overwhelming, disorienting, and at times scary. Preparing yourself for how to stay calm and developing a strategy for how to find a rhythm early in the race isn't a bad idea.
In terms of training, swimming with a group of people (even a small group) will help prepare you for the necessary maneuvering and occasional bump that you will mostly likely experience during a race. Also, become comfortable with other strokes. In particular breaststroke and backstroke. It is a good skill to have if you ever need to keep your face out of the water to either survey your surroundings, identify your location, or simply collect yourself when out in open water. And on race day, there is always the option of hanging back and letting the more aggressive athletes go ahead of you. You can also stay to the far outside of the group to avoid the masses. That additional 30-45 seconds could save you a big headache and a kick in the ribs.
Wave Start
Wave starts break the field up into groups or heats (men/women, pro/amateur, age groups, etc) and the waves are set off a couple of minutes apart. The size of the wave will depend on how the race director decides to break up the field. While you will still have to deal with swimming in a group , because the group is smaller in a wave start swimmers will space themselves out more quickly, making it easier to find your own space and pace early in the race. Many triathlons and all open water swims (that I can think of) start with either a mass start or a wave start.
Time Trial Start
In a time trial start, which is not uncommon in triathlon, racers line up according to their race number and an official sets competitors off a few seconds apart either one at a time or in pairs. It makes it harder to tell where you are in terms of place throughout the course of the race, but it is the least anxiety-inducing start method and the odds of your goggles getting kicked off your face are much, much lower.
Entry
Keep in mind that all of the below can be coupled with a mass, wave, or time trial start.
Beach Entry
Beach entries are common with lake and ocean swims. In this situation the group starts on land and runs into the water. Practicing this kind of entry before the race will be very helpful on race day, and any time you have a chance to do an open water swim in training take the time to do a few entries and sprint swims to about 100 yds off shore. Becoming comfortable with running in shallow water, dolphin diving, and determining the depth at which it is best for you to start swimming will make the start of your race flow much more smoothly. Also, on race day before you start, it's not a bad idea to get in the water and see what the ground is like (sandy, rocky) and whether or not there is a sudden drop off or any large holes.
Water Start
Many open water swims and mass starts for triathlon start in the water. These starts can be in waist or chest deep water, or deep water. Deep water will require you to tread water or float (pretty easy in a wetsuit) prior to starting. Practice for this can include standing at chest deep water in the middle of the pool and working on pushing off the ground into a sprint, or treading water in the middle of the pool and starting your swim from a stationary floating position. Get comfortable going directly into a sprint from a dead stop. It can be a little bit awkward, so the more practice the better.
Dive Start
This is less common for amateur triathletes (though elite waves will often be set off this way) and I only know of a handful of open water swims that begin with a dive. That being said, if you find yourself in a race with a dive start and aren't comfortable diving, there are a few things you can do:
Tighten your goggles more than you usually do, and put your goggles on before you put your cap on. Both of those can help reduce the odds of you losing your goggles at entry (though, to be honest, if you can't keep your goggles on when you dive in I would highly recommend point #2...)
Jump feet first. You don't have to dive. You just need to find a way into the water. If you decide to take this route I would also recommend...
...hang back (the old crowd favorite). Let others go in front of you. You might lose 30 seconds in your race, but you could be saving yourself a lot of strife and anxiety.
The swim is the most stressful part of the race for many triathletes, and the start is often the most unnerving part of an open water swim. Take your time. Find a way to stay calm. Keep an eye out for other swimmers who don't look comfortable and give them space. The race is long. Don't use up all your energy in the first minute.