If you're familiar with Southern Maine at all you're probably familiar with Crooked River. Crooked River is the longest tributary to Sebago Lake and eventually flows into the Casco Bay via the Presumpscot River. The river gets its name because its wicked crooked, obviously. I personally have gone down parts of Crooked River via kayaks and boats and it is not the way to travel if you're in a hurry. The winding river often makes you feel like you could easily walk a much further distance in less time than to float down stream. The upside to Crooked River is that you're going to see a lot of interesting things along the way.
Below are some pictures I took on River Road in Naples, Maine at the Jeff Plummer & David Hancock Memorial Bridge which I believe is used as a snowmobile crossing in the winter. You can find more information about Crooked River here.