The Contoocook river is a great place to go Canoeing. The river is very different in high vs. low water conditions. High water conditions provide for some very big rapids and fairly unsafe conditions for regular paddlers. However when the water is on the low end many of the rapids are still passable and lots of fun.
When the river is very low it can also be a good place to go rock jumping. The location of all the big rapids has tons of rocks scattered across the river bed. Due to the low water you can strategically jump / hop from rock to rock and make your way across the river. It’s surprisingly fun! Checkout the American White Water link for the locations of all the big rapids.