Islington Tunnel is 878m long and takes the Regent's Canal under the Angel area of Islington. The tunnel was opened in 1818 and has no towpath. Before canal barges had their own built-in source of power (either steam or diesel engines) barges had to be legged through the tunnel. This meant that men had to lie on top of the barge and push the barge through the canal with their legs - no doubt quite a tiring job in a 878m long tunnel!
Later on a chain on the canal bed was fitted to haul barges through pulled by a steam tug and later diesel. The chain went out of use in the 1930s, by then most barges could get through the tunnel without any help.