Just 182 yards in length and built by Reed Bros of London, curvature prevents one end of the tunnel being seen from the other. The first train to climb its 1:80 rising gradient towards Chepstow did so on 1st November 1876; the last one enjoyed the experience on 6th January 1964.

Plans have been approved for the tunnel to become a footpath. The southern Portal comes out on the river wye where the railway bridge once stood leading to Tintern Station