Mine shaft chaser Raymond Shaw has been pinned under a 200 kilogram rock and felt others break and splinter on his jaw.
The founder of the Victorian Historical Mine Shaft Chasers began exploring mines as a child.
He has abseiled to 220 metres below ground – almost as deep as the mine shaft which opened up at Sebastopol last weekend.
The mine shaft chasers crew includes geologists, professional climbers and riggers.
“I’ve had some rocks as big as your head fall down from 30 metres above and they just explode when they hit you,” Mr Shaw said.
“I’ve had them pin me down to the ground.”
The Melbourne-based stone mason has rolled a rock weighing a couple of hundred kilograms off his helmet.
Most rocks have been softened and cracked in the sun and fragment on impact, Mr Shaw said.
“I didn’t panic, I just lay there.
“I felt around over the top of my head and realised that something was pressing down on my helmet and holding me to the ground, I pushed it off and then it rolled down behind me.”
Other times he has felt himself become light headed from the presence of carbon dioxide in the tunnels.
An exhaust fan runs off his generator to blow fresh air down the shafts.
“I’ve had a couple of instances where I’ve had carbon monoxide in the shaft and I’ve been worried I won’t make it back it up.”
Images of the mine shaft at Sebastopol were a hit for the Victorian Historical Mine Shaft Chasers Facebook page, which has over 5000 followers.
Dean Anthony, the group’s photographer and a digital analyst when above ground, has done some abseiling down shafts but prefers the walk-in mines.
“You’ve got to be very careful.
“It was really scary because you’re climbing backwards down this great big hole that disappears into the ground forever.”
Mr Anthony has seen old pumps, rusted mine carts and bridges between underground tunnels.
“It’s just interesting because of the history of them, it’s like travelling back in time.
“Sometimes we know someone hasn’t been in there for well over 100 years.”