Fenix 5 and Polar H10 during swimming

The problem would be transmission in the water. The HRM-Swim batches the data and send it to the watch when you get out.

Unfortunately there is no standard for store-and-forward of HR chest-strap data. So while a number of manufacturers (including Polar) have swimming compatible straps, they only work with that company's head unit/watches. The Fenix will work well with Garmin's HRM-Swim and HRM-Tri, and while it will get the H10 data out of the water, it will not receive the stored data from swimming.

With HRM-Swim strap (connected by ANT+ technology) it works like this: You can check your actual HR, but you need to get your strap above water. You will get then your HR immediately.
Dont know if it works also by Bluetooth straps like Polar, Suunto...etc.

Thanks for your answers.

So I don't really have a choice - need to buy hrm-swim

Btw
Can I use it for running, too?
:)

KrzysiekJar Yes you can use it for running too but it's not particularly comfortable - are you swimming indoors outdoors or both - if only outdoors then get the hrm-tri - its more comfortable for running but not chlorine resistant like the Swim and won't stay in place for pool swim push offs from the wall

If it's constant HR you want while you're swimming then I'm not sure whether the Swim will give you what you want - it can only connect to the watch when it is above water so will mainly connect when you stand up in the pool at the end of a set - the rest of the time it may connect intermittently

What it does do well though is give you a good record of your HR in the swim that you can review afterwards in conjunction with the activity

Thanks for your suggestions.

I swim mainly in a poll.
I'm still thinking about getting Polar H10
I'm still not sure if I could export somehow swimming data into garmin app
;)

I'm using since 1 month Polar OH-1 optical heart rate from Polar. I have tested many optical heart rate for swim and nobody of these work good. Polar OH-1 works flawlessly instead! I wear on my forearm and even if i can't save data in a fit file, i can see always my instant heart rate. Another cool feature of this OH-1 is that it can cache heart rate and you can download data after swim session with Polar Flow! So it can transmits heart rate with BLE or ANT+, cache data and you can also view instant heart rate! I think it's much more comfortable to wear compared to HRM-Swim (that i own). The only downside is that data from Polar Flow can'be merged with fit file of Garmin, the only software that permit this is SportTrack, but is' a payment software and you have always to combine data manually...

I'll probably get h10 (cheaper and Good reliable)
I hope I manage somehow implement the data i to garmin
If you have any experience in this matter let me know
:)

The new Scosche Rythm 24 (Released April) will give the functionality you are after...