Open water swimming - wrong distance measurement

I have the same problem with my new Swim 2 (Software version 2.8) The route and timestamps are correct, but the distance calculation is completely wrong (with factor 1.45) . The units are set to metric. When I export the gpx file and import it again in Strava, the distance is perfect.

Yes, I also calculate the distance incorrectly.
But I have a nice map for checking distances: www.freemaptools.com/measure-distance.htm

meanwhile I've had a software update. But I couldn't check ist with swimming dates. So I tried when driving a car - distance measurement worked (more or less - speed was too high). Maybe, I'll check when I go for a walk with "freewater"-setup.

L.HY said:

I tried when driving a car

L.HY said:

I'll check when I go for a walk

Neither of this will be a meaningful test, because contrary to real open water swimming, during driving or walking there is unrestricted access to GPS signal, so test conditions are fundamentally different.

Air temperature ist below 10 °C, I won't try this in the lake, now. In summer, with the watch inside of a buoy, signal isn't restricted,either, but measurement had been wrong, anyway.

Did this fix it? I’m having the same experience with my 945 Forerunner. When I export to gpx and re-upload it is correct - but it’s unhelpful for me to track my pace whilst swimming. 

I have a similar problem on Fenix 6. Mine underestimates distance by 10%. Importing from GPX fixes the distance

Yep - mine too. Forerunner 745. I've been puzzling over this for months and tried your suggestion of uploading GPX and it fixes the distance. 

I'm also having this problem. My friend and I both have the same watch, swim the same route and her distance is twice what I'm doing!!
Can you tell me how I can export the gpx file?
Thanks

In Garmin Connect: support.garmin.com/.../