Along with the practical dangers, Ioan admits he keeps an open mind about what other things might lurk in the darkness.
"I have had some things happen underground which I can't explain," he said.
"Miners were always very superstitious. They believed in all sorts of mine goblins and guardians and such."
Ioan said one of his most frightening experiences was when he was alone underground and heard another group approaching down the passageway.
"Quite often you'll run into other explorers who have come in through another entrance," explained Ioan.
"I heard a group of other explorers coming towards me, I could hear their footsteps but when I went around the corner, I couldn't see anybody there.
"I shone my torch straight ahead, you could see for hundreds of feet, but there was nothing. And these footsteps, about ten of them, just walked straight past me."