http://www.nps.gov/choh/planyourvisit/great-falls-canal-boat-rides.htm

The C&O canal used to run 184.5 miles and there are very few sections that still have water in them. There are a a couple of places where they have canal boats for tourists, and Great Falls is one of these places. During the tourist season, the boat at Great Falls is actually drawn by mules owned by the NPS.