How to calibrate pool swimming function (laps counting is very inaccurate)?

Hi

Apple Watch is designed to improve the accuracy of estimations for swimming workouts over time, based on ongoing analysis of your stroke efficiency. It is not possible to manually calibrate the watch for swimming workouts.

For more accurate lap counting, you may find that it helps to make firmer contact with the end of the pool each time you reach it.

Note also that Apple Watch relies on arm movements for monitoring strokes and distance, so estimations may be affected by the use of training aids (eg wearing fins) and when not using your arms at all (eg when using a kickboard).