The Woodhead Tunnel on Table Mountain
The Woodhead Tunnel is a 640 metre tunnel that goes right through Table Mountain between Orange Kloof and Slangholie Ravine. It was built between 1888 and 1891 in order to divert the water from the Disa river to the Pipe Track and hence to the Molteno reservoir in Cape Town.
Although it has been out of use for some time parts of the Molteno tunnel can still be seen. The entrance is found in Orange Kloof and is not barred.
Once inside the tunnel is about 1.5 metres high and once you have taken a few paces inside pitch dark. I have heard of people who have explored far into the tunnel but I have usually exited fairly quickly. Even with a torch you bang your head at regular intervals on the uneven roof above.