I currently own a FR 645 and have used it mainly for running and cycling up until now.
I've recently started swimming and want to track the activities (mainly for effort in the form of a raised heartrate as that's what seems to give calories burned estimation).

The FR645 does not record heart rate when using the pool swimming profile, so that's a non-starter. I've been resorting to recording it as a treadmill activity then editing it to change the type in Strava as that way I get my heart rate metrics, but of course, the distance calculation is a mess. Such a pain.

Looking at the FR255, I have read people saying they use it in pools and it sounds like they get HR data, but the Garmin website states that you only get HR data in swimming activities if you use an external HR monitor / band.

Can anyone recommend a model that does what I'm after?