Substantial remains exist of lock l7 and of a dry dock which was
added to the lock platform after l875. The lock by-pass was used to drain the dock when required for the maintenance of boats. There are also remains of a pitch boiling hearth and of the timber uprights which supported cross-pieces to carry boats under repair.
(Site entry from "A Guide to the Industrial Archaeology of the Swansea Region", Association for Industrial Archaeology, 2nd Edition, 1989)
J Hill 24.10.2003

Lock 17 or Pant-y-ffynnon Lower or Thick Lock (18,370m from Swansea Basin) This was the first lock of the Godre'r Graig flight proper. It is in good condition with foot grips on the eastern lower gate balance-beam platform. A dry-dock was added to its by-pass in 1875-76. The winding stair down the lower face of the lock podium is unique. This is one of only two locks with stop-plank grooves halfway along the lock chamber. The east wall is patched. Stop-plank grooves may be an original feature that has disappeared from other lock-chambers during regular rebuilding. This feature at Lock 6 at Clydach has been masked by later rebuilding.

Lock 17 SN 7583 0737

Stephen Hughes,14.08.2006.