Pair your Apple Watch and iPhone.
Make sure Bluetooth is enabled and your devices are connected.
Open the Tangent app on your iPhone.
Start a round on your phone.
If your watch is connected, it should automatically launch in GPS mode.
If it doesn't, tap the Watch icon on your phone app to manually activate the watch.
Note: It may take 30–60 seconds to fully load, as a lot of data is passed from phone to watch.