> Note that the ANT and ANT+ transmission protocols that the Ambit2 utilizes to transmit heart rate don’t transmit well underwater (about 1-2”), thus, you won’t get any heart rate data.
I believe Polar's ultrasonic sound transmission is still the only one which works reliably underwater.
The Ambit2 S does not do that. The new Ambit3 does it though. The strap works underwater, too. It buffers the data and sends it later when bluetooth connectivity is back...