Make sure that after you finished your surf, you “STOP” the surf session on your Watch. The synchronization will then happen automatically when your Apple Watch is within reach with your iPhone.
Still not synchronizing? Make sure your Apple Watch and iPhone are connected. You can do this by swiping up from the bottom on the home screen of your Watch. A green iPhone icon indicates your Watch is connected, a red icon indicates it’s not connected or paired correctly.
If you’re experiencing connection or pairing problems with your Apple Watch or iPhone, please read more instructions on the Apple Support page.