Automatic route with waypoints

I have always added routes by clicking on the map and adding waypoints. Today I was adding a new route and clicked new then clicked the start point on the map. When it popped up and asked where I was starting from, it plotted to whole trip(not as the crow flies). WOW! how did I do that and how do I do it again? I deleted the route because it put me going outside and I wanted to go inside, but it plotted going out the inlet marker by marker and coming back in the other inlet. Please oh please tell me how I did that because now I cant recreate it.