The Exeter river is a great river to float down on. There are a few places where there is white water but most is water meandering down. I have never seen so many turtles. This river has fishing, boating, swimming, bird watching and so much more.
Here is a good write-up of the river http://des.nh.gov/organization/divisions/water/wmb/rivers/exeter_river.htm
Here is a listing of the fish that inhabits the river http://www.nhfishfinder.com/exeter-river-13921-location.html
Here is an adventure of a family undertaking the Exeter river. It is full of pictures and shows the enjoyment of boating the river http://outdoorsbycracky.blogspot.com/2013/07/paddling-exeter-river-perfect-family.html