Can I wear a chest strap for swimming?

Some can. The Polar H10 stores workouts internally and works underwater but Bluetooth doesn't transmit through water in real time. The Garmin HRM 600 advertises swim use with onboard recording. Reddit users on r/Garmin caution that any strap used in pools needs aggressive rinsing to avoid odor — a complaint that comes up repeatedly with the older HRM-Pro Plus.