Tapering is all about reducing your training workload and resting in the lead up to your main competitions to ensure that you’re in the best possible shape to go for gold! Tapering = less exercise. Less exercise = more free time on your hands. Sometimes pre-race anxiety hits you in your new found free time.
Use your time too mentally prepare for the race. Think about the positives (how much fun you will have, how great it will be to finish) but also take time to plan for unexpected problems. Have plans in place so that you don’t have to think about any problems, you just react. For example: Plan to take two sets of goggles, trunks, hats etc to competitions, practice dives, turns and finishers. Get lots of sleep. Stay relaxed and happy!