Always Wear a Wetsuit
Wetsuits are your best swimming friend. Not only do they keep you warm in cold water, but they make you a much better swimmer.
Why? Because wetsuits make you more buoyant, and the higher you swim in the water, the faster you go.
Recently, the international federation in charge of swimming banned all new swimming wetsuits and speed suits because they provided such a huge advantage that swim records were tumbling like snowflakes from the sky.
Fortunately the sport of triathlon allows you to wear a wetsuit when racing (unless the temperature of the water is too high) so take advantage of this great swim buddy.
The triathlon swim is by far the most stressful part of the race, but don't let that scare you.
There are plenty of boats around to help you. In a triathlon you can legally hold on to a boat and not be disqualified. Think of it like sitting down on the run. There's no rule against it.
If you panic, just grab a boat, calm down, catch your breath, and start swimming again when you are feeling better.
Search for your next triathlon.