Below the bottom lock was a long level pound stretching to beyond Blisworth Tunnel. The seven locks raised the level of the canal by to a fairly short summit pound, which passed through Braunston Tunnel and then descended through five locks to Braunston. The locks were built wide enough to take two narrow boats side by side, in the hope that the canals beyond the northern terminus could be persuaded to widen their locks and that wide barges carrying 70 tons could be operated.