Garmin Swim 2, GPS Swimming Smartwatch for Pool and Open Water, Underwater Heart Rate, Records Distance, Pace, Stroke Count and Type, Slate Gray, garmin swim 2
Garmin introduce underwater heart rate monitors
Garmin Swim™ 2 | Swim Watch
Garmin HRM Tri and HRM Swim heart-rate monitors - 220 Triathlon
Forerunner 920XT - Replacing the HRM-Swim Battery and the HRM-Tri Battery