Indeed there are, depending on what sort of mines you are talking about. There is the Poverty Reef decline, relatively modern and now abandoned. Orienteers aren't going to see this though. Its all fenced off with a serious fence. But out there in the old mining areas there are a couple of adjacent hills that could be described as honeycombed by shafts. Here is the largest. Multiple entries and scaringly deep. The photo doesn't do the place justice. Its like a cathedral of rock. It is surrounded by a flimsy fence. Not going to be on any orienteering course. You have to click the photo to get the full view.