>>2151371The Paw-Paw Tunnel is on the C&O, and has some interesting history.
It was built with slave labor, as most things were in America of that vintage.
There is an incident where two canal boats entered opposite ends of the tunnel and met in the middle. Both captains insisted that they had the right of way, and that the other barge should back up. This standoff went on for several days, and was resolved when an officer of the canal company started a fire at the upwind end of the tunnel and threw green stalks onto it, eventually smoking the stubborn barge captains out.