Hello J, During the summer of 1992 I camped at Perranporth. I noticed a hole in the cliff face at Droskyn head. A friend and I entered by climbing the cliff and over a wooden barrier with a big red sign saying danger. I was incredibly naive and stupid and proceeded to explore with a small torch. A roughly shaped tunnel approximately 2 metres wide lay ahead. After a short distance, to the left was a round shaft about 6 metres in diameter. It rose to the cliff top where it was capped with railway sleepers, grass was growing through. It dropped about 8-10 meters to a water surface. A short distance further on and blocking the main passage was a similar shaft. However, to one side was a concrete ledge less than 0.5 metres wide, leading to a well defined passage that was less than 1.5 metres high by less than a metre wide. I enthusiastically followed this in a crouch, my friend holding my hand crouching behind me. After several metres, I felt a gust of wind and a six sense told me to stop walking. My eyes grew accustomed to the darkness, and I found my toes were over the edge of a large rectangular shaft. It was at least 6 metres by 8 metres. Again it rose to the cliff top and was capped by railway sleepers. I lay down and shone the torch down the shaft. There was no noticeable bottom. Approximately 100 metres down was a wooden shaft attached to the wall, apparently the remains of a man engine. I found a large stone and dropped it, it eventually 'flew' into the wall and bounced all the way to the bottom. I hope this is of some interest to you. My blood is running cold writing this and I realise that I had a very lucky escape.