Suggestions for Heart Rate Monitors that work in the Pool?

Can anyone recommend a heart rate monitor that works in the pool? I have a Garmin monitor with chest strap which is waterproof, but the transmission doesn't work in the pool. With the Garmin, I can get out of the pool and get a reading, but not while I'm in the water. I've searched the internet and have found very little info on monitors that will actually continue to take/transmit while in the water. I've seen people mention the Polar s720i, but that model is no longer made. Ideally, I'd like to find a monitor that stores your heartrate readings throughout the workout and will download to a laptop AND works while you are in the water. I'm 47 and had a heart attack a few years back, so I'd really like to have an accurate monitor while I'm swimming. Thanks for any help you can offer. RS in New Orleans