To be honest Apple's swimming pool and open swim tracking is some of the best we have used after the Garmin Vivoactive 3 Music. Best cellular connectivity If you want standalone smartwatch there is no one else that's offering better right now of course apart from the more expensive Apple watch series 4.
15 Best Triathlon Watch Review. Garmin Forerunner 920XT – Best Selling Triathlon Watch; The black and blue Garmin Forerunner 920XT with HRM-Run Monitor containers many advanced training features into a watch. It is about 15% lighter than its predecessor, the Garmin 910XT.