If you have your Apple Watch, but not your iPhone
You need your iPhone to get the most out of your Apple Watch. If your iPhone is off or you don't have it with you, you can still do these things.
Track your workouts with the Workout app.*
Track your goals with the Activity app.
See the time and use the Alarm, Timer, and Stopwatch apps.
Use the Music app to listen to synced playlists on your watch.
Display photos from synced albums in the Photos app.
Make purchases with Apple Pay.
See your current heart rate.
Relax and breathe mindfully.
If you have a Wi-Fi connection
When your iPhone is off or out of range, your Apple Watch can use Wi-Fi networks that you've connected to previously on your iPhone. If your watch connects to one of these Wi-Fi networks, 
appears in the Settings glance and you can also do these things.
Use Siri to get directions, send iMessages, and more.
Send and receive messages using iMessage.
Make and receive phone calls if you can use Wi-Fi calling.
Check the current weather.
Track your stocks.
Control your home.
Use apps that support Wi-Fi.
Set and respond to reminders.
* For GPS accuracy when you walk, run, or cycle outdoors, select the appropriate Workout and bring your iPhone. For indoor and outdoor walking and running, this will also help calibrate the accelerometer in Apple Watch for times when you don’t have GPS. For GPS accuracy, you can also calibrate your Apple Watch. Apple Watch Series 2 has built-in GPS that allows you to get more accurate distance and speed information during an outdoor workout without your paired iPhone.