Select your product to confirm this information applies to you
Unable to Edit Pool Size on Garmin Swim
The Garmin Swim allows you to setup the size of your pool to track the distance of your swim activities. If you cannot edit this pool size, there are some things you can try to resolve it.
Steps to try:
Master Reset watch. Press and hold, MENU + TIME + UP (it is recommended to backup your data with Garmin Express before resetting).
Your watch will now let you set a different pool size.