Start by tapping on the map tools menu expander button:
Next, tap on 'Measure Distance':
Follow the on screen prompts. Try to keep both points within the bounds of your screen. After you select 2 points, you will see the distance, in river miles, between those 2 points and have the opportunity to save the measurement as a Route:
You can name your new Route, add some notes, and save it to the Saved Tab:
View your newly saved Route in the "Routes" section of the Saved Tab:
You can also tap on any Point of Interest and start the measuring process by tapping the "Measure" button:
