Garmin Swim 2, GPS Swimming Smartwatch for Pool and Open Water, Underwater Heart Rate, Records Distance, Pace, Stroke… Price: $249.99 (as of 08/07/2021 01:25 PST- Details)

GPS swimming smartwatch for the pool and open water
Monitors underwater estimated wrist-based heart rate during swim activities
Pool swim mode: records distance, pace, stroke count, stroke type and SWOLF (gauges swimming efficiency)