My Garmin Fenix 3 HR is a wonderful, and oftentimes frustrating, tool. I discover new ways to use my Fenix 3 on a regular basis. It is one of two watches I wear regularly, the other being my Apple Watch.

It is sometimes really frustrating, too.

One of my recent frustrations is more me than the watch: battery life. I learned recently that at my excessively slow pace my Garmin Fenix 3 HR can’t track a whole Ironman. Doh. Nearly 16 hours tracking heart rate, GPS and bike metrics it just didn’t last.

On a more everyday basis, I’m frustrated when my Garmin Fenix 3 HR drops lengths in the pool. I say every day, but it’s more like 2 out of 3 days — still pretty frustrating.

In essence, what happens is I’ll get to the end of a lap (down and back in a 25 yard pool) in the pool and I’ll look down and see a multiple of 25 rather than a multiple of 50. As Charlie Brown would say “Aaaaargh!”.

Don’t get me wrong, I’m not one of those people who lives or dies by metrics. I mean, as a 50 year-old heart patient triathlete with only 4 years in the sport, I’m not looking to be on the podium any time soon. But, it’s annoying AF to not have the right numbers when you’ve got this miniature super-computer on your wrist.

So, after much searching I found the answer to my Garmin Fenix 3 lap dropping frustration. It’s a site called Swimming Watch tools. In essence you can download your data from Garmin Connect and then re-upload to Swimming Watch Tools to manipulate it.

Here’s how you do it.

First, download your data from Garmin Connect:

The output from the Garmin Fenix 3 HR by way of the Garmin Connect web app is a “.fit” file.

From here, you can start to use Swimming Watch Tools to manipulate the data. The site has a pretty extensive User’s Guide, but I’ll go through some quick basics.

Uploading the data is super simple.

Choose the .fit file from the workout you want to modify.

Once uploaded you can open the editor.

This was a pretty clean file, but you can edit a number of items as needed.

• If you dropped a length, you can find the extra long length and “split” it.
• If you think you may have added a length you can find the two short lengths and “merge” them.
• You can edit the stroke type Garmin automatically detected.
• And a lot more — check out the Swimming Watch Tools User’s Guide to see everything you can do.

Once you’re done manipulating the file, you can re-upload it to Garmin Connect. One caveat is that you have to delete the original before uploading. This is pretty scary the first time you do it, but great news is if you followed the steps above you’ve got the file on your computer.

Uploading looks like this:

I’m sure if I were a better swimmer I’d have fewer dropped / additional lengths on my Garmin Fenix, but until I have a perfect turn and push-off on every lap I’ll be using the Swimming Watch Tools a couple times a week.

I hope you find it helpful. If you have a second, please share your favorite Garmin Fenix 3/5 tips and tricks in the comments below.

Happy swimming!