Manitouwabing River - While seldom run this is well known by the Parry Sound paddlers and fun in the spring or fall when the water rises. Paddling from below the dam, there are a 2 small drops which punctuate areas of flatwater. The third drop you come to is a slide leading into a 6 foot fall. There is a hunt-camp sign on the RL shore, which is the spot to scout from. Carry back up the RL side to do laps.
You will paddle a bit of moving water before coming to the next drop. The river is funnelled down a narrow chute on the RR shore, with a fairly big hole in the entry. (It looks to have a likelihood to slam you into the wall and may become a 'room of doom'). If you choose to walk around it, you can seal launch into the chute off the cliff from the RL side (fun).
Two other significant rapids occur after this, with some 2-3 boogie rapids and flat in between.
The first larger rapid is a series of holes (which can be avoided) culminating in a large hole/crashing wave at the bottom (C3).
The second rapid of note has some C3 water leading to river-wide ledge with a tongue in the middle and a boof move on RR. (This might be the rapid named 'Ragged Rapids' on topo maps.)
There is a bit more flatwater before a large, rarely run falls. Portage on the left into the lake that forms the confluence of the Seguin and Manitouwabing. Hang a left and paddle about a mile up the Seguin to the takeout (RR DS) on McDougall Road.
An alternative exit is to continue West ending at Badger's Corner. This gives you the opportunity to investigate the interest or not of "Mountain Chute" and some other smaller rapids. Total distance this way is about 14 kilometres.