There are plenty of heart rate monitors available on the market. Not all of them are designed to be used in the pool. The HRM-Swim by Garmin is different. It has a durable, compact design, making it ideal to use in the pool. It stores heart rate data underwater and forwards it after the swim to a connected compatible device. The device sends real-time heart rate and interval summaries to a compatible watch.
The HRM-Swim has a battery that lasts up to 18 months. It stores up to 20 hours of heart rate data during your swims. The device is compact and durable. You will need a CR2032 battery to get it to work. Costs $99.99 at this time.