Get a swim coach
You will gain much more from improving your technique than from increasing raw strength or endurance when it comes to swimming. Learning proper technique should be your number one priority, and there’s no faster way of doing that than hiring a swim coach. A great coach that has experience with swimming in open water can be hard to get, so let’s look at some other tips in case you have to go solo.
Learning to swim is like figuring out the best aero position on the bike
Cyclists are used to powering through workouts, but in swimming you’re much better off starting with form drills and laying a solid foundation for your technique. Don’t fight the water! Think of swimming as figuring out the most “aero” dynamic position on a bike, just in water and without a bike.
Focus on a streamlined body position in the water
Freestyle (front crawl) is the preferred triathlon swimming style because it allows for the least drag in the water, and a streamlined body position in the water is the best way to achieve that, just ask the fat guy going three times your speed at the pool.
Cyclists often have very muscly, large legs which can have a tendency of sinking, thus making it difficult to keep a good body position. Your core muscles and glutes will allow you to balance and prevent your legs from dropping. It is essential to first focus on drills that help develop an elevated and horizontal body position and teach you to activate these muscle groups.
What does a good triathlon swim technique look like?
Triathlon open water swimming is quite a bit different from pool swimming. There are many subtle differences, but the biggest one is that you have to learn to navigate. You can practice that in the pool by going a few strokes with your eyes closed, then trying to lift your head out of the water slightly just so you can see where you are, correcting your trajectory, and repeating again. Look at this video of a triathlete doing this drill in the pool.