Start by tapping on the Measuring Tool button:
You can Free Draw your route or Snap to River:
Follow the on screen prompts. After you select 2 or more points, you will see the distance between those points and have the opportunity to save the measurement as a Route if you are an onWater Plus or Pro user:
You can name your new Route, add some notes, and save it to the "You" tab:
You can also tap on any Point of Interest and start the measuring process by tapping the "More" --> "Measure":
