Mines are inhospitable, dangerous places, so entering Potosi's active silver mine was a terrifying prospect - with no safety regulations, tourists visit at their own risk. The mountain is called Cerro Rico, "Rich Hill" but would be better described as "Hell Hole". We entered through one of 400 tunnels and stooped and crawled up to 3km into the heart of the hill, with the very real threat of being trapped, buried or crushed at the forefront of our minds.

The mine is still working. We witnessed the miners working in the most gruelling conditions imaginable. In the tiny tunnels they were using primitive techniques to hack away at what little silver was left. They would then push their cart load of ore, weighing over a tonne, the several kilometres back through the tunnels to daylight. Our guide, a ex-miner himself, helped us chat with the miners. Many of them started working in the mine as teenagers and earn just £5 per day for their hard graft. They were all chewing coca leaves to give them the energy they needed for the back breaking work. We learnt that after just 10 years most of the miners will develop silicosis (black lung disease).

For us it was hard to imagine a more unappealing job, but life in the mine used to be much worse. Our guide explained that 300 years ago, the Spanish used the local people as slaves to extract vast quantities of silver and then shipped it to Spain. To speed up the process they even used slaves from Africa. Naturally, the slaves didn't live long and over a few hundred years up to 8 million people died while mining tens of thousands of tonnes of silver from the "Rich Hill". At the time, it was the largest source of silver on the planet and practically bankrolled the entire Spanish empire.

As we headed deeper into the labyrinth of tunnels, the temperature began to rise and we quickly began to drip with sweat. Apparently the sulphur in the rocks gets exposed to water and the chemical reaction generates heat - very unnerving! Even more unnerving was when we came across a shrine to the devil, with a life size figure of the beast himself. Being deep underground and so inhospitable, the miners believe that the devil owns the minerals they are taking. In order to appease him, they place lit cigarettes in his mouth, beer at his side and coca leaves at his feet. Seeing this figure with it's horns, black teeth and scary eyes, surrounded by beer cans, sitting in a corner of a dark tunnel, deep underground was a little unsettling to say the least!

As we emerged from the mine we have never been so grateful to see daylight. But the danger wasn't over - our guide was keen to demonstrate the power (and danger) of the crude dynamite used by the miners. He broke up the traditional dynamite "stick" and mixed it with petrol pellets. As he lit the two minute fuse, he passed the bomb to each of us and insisted we have a photo taken before it blew up! Utter madness, but Bolivians are crazy people. With the photos in the can, our guide placed the bomb on the ground a safe distance away. Even through we knew the explosion was coming, it's force still took us by surprise ... it was massive and shook the ground we were standing on. A huge cloud of dust erupted from it's source. It was a harsh example of how dangerous life in the mines actually is.

Visiting Potosi's Cerro Rico silver mine was a dangerous but eye opening experience. It was certainly the first, and possibly the last active mine we intend to visit.

Check out ‘Bolivia - Potosi’ at http://gallery.me.com/peterjprice/101854