All exploration of mines, caves and many other underground features as well as aboveground should only be undertaken be people who know what there doing.
I do not encourage anyone to visit the abandoned places iv explored, in some cases there is a danger of seriousinjury and or death!
The Canterbury Cave, My greatest challenge yet! A crazy system of natural tunnels inside the cliffs at St. Margaret's Bay, Dover.
This link will give more info into the caves:
http://www.phon.ucl.ac.uk/home/dave/personal/cave/canterbury.htm