This stop lock (the only one I have seen on the trail so far) is near where the Billy Goat Trail exits on to the towpath. The stop lock was used to prevent flooding of the canal. Note that the towpath itself is currently closed for repairs south of the lock. One has to take the bridge over the canal that you see in the picture and follow the Burma Road trail past Widewater in order to hook up with the towpath once again at Anglers Inn.