Canals had their commercial heyday in the UK in theVictorian era, but many have now been reopened and may be carrying more people (not freight) than they ever have in the past.
To navigate canals, of course, you need to go through locks (with the notable exception of the Union Canal). Sometimes these locks are powered by machines, sometimes they’re powered by people.
I guess that lock 3 on the Forth and Clyde Canal is powered by people.
To apply that power you need a quarter circle of bricks, with raised ones to brace your feet against, a solid plank of wood acting as a lever, and one willing person to push. Or even betterm two willing people – one for each side of the canal!