by Paul Williams, Production Crew, December 2009

It’s 50 degrees C [122 degrees F] and has a humidity of 100%, less than a hundred people have been inside and it’s so deadly that even with respirators and suits of ice you can only survive for 20 minutes before your body starts to fail. It’s the nearest thing to visiting another planet — it’s going deep inside our own.

For How the Earth Changed History I have been lucky enough to film everywhere from tiny Pacific islands to the centre of the Sahara desert, yet nowhere could prepare me for filming in the Giant Crystal Cave — Cueva de los Cristales of Mexico.

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Probably the most incredible photograph of the cave ever taken. Photograph by Carsten Peter/Speleoresearch & Films


Highway to Hell

My director, Nigel Walk, and I arrived in the quiet town of Naica as the morning sun painted the Chihuahua desert a golden hue — it was a serene moment of calm that wasn’t to last long. Within minutes we were inside the mine complex tumbling and bumping our way downwards, deep into a subterranean world. The air became dusty, thick and heavy, my skin tingled as sweat exuded from every pore — deeper and deeper we went. If you were a miner in these unforgivable tunnels you might refer to this road as the highway to hell, but for the few outsiders who have made the journey it’s a right of passage to see one of the world’s most magnificent natural treasures.

One-thousand feet down, we arrived at the control room where conditions were already an exhausting 45 degrees C [113 degrees F] and 55% humidity. Here we were greeted by Gonzalo Infante of Speleoresearch & Films, a larger-than-life character whose contagious passion for this inhospitable place had allowed us to come this far. For more than five years he has tirelessly worked to share the wonders of Naica with the world and to preserve them for future generations. It was his experience, and a 15 man team, that would keep us alive as we filmed this geological wonder.

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The control room. An exhausted team member gets assessed in the medical area.


“You think this is hot,” said Gonzalo gesturing towards a vaulted iron door; “this is just a cool breeze compared to what you’ll feel like in there… ready to go?” At this point I had expected to be stepping into an oversized bright orange ice-suit and putting on a huge respirator backpack. Everyone else seemed to be dressed like characters from Ghostbusters, but Gonzalo insisted that our first visit should be a completely raw experience, allowing us to physically and mentally prepare, just in case, for whatever reason, we should end up spending much longer inside than we had anticipated … anxiously we heaved open the door and entered.

Entering the Chasm

Nigel and I intrepidly stepped forwards — to say that the heat hit us like a wall would be an understatement; my glasses steamed up and their metal frames almost burnt me — I had to leave them at the entrance. A slightly fuzzy view however did not perturb my sense of awe. I was dumbstruck. A torrent of sweat streamed from my head, my energy was being sucked away, and my breathing became heavy. The view was enthralling, my eyes led me forwards, but my body wanted to retreat. I was dwarfed by a forest of giant gypsum crystals, some up to 12 metres [40 feet] long — the largest crystals ever discovered, some estimated to weigh as much as 55 tonnes. It was something that had to be seen to be believed and I was doing just that… however, within just five minutes, I had gone from a reasonably fit 30-year-old to an asthmatic 60-year-old — it is the antithesis to the elixir of life!

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Wearing the ice suite and cool air ventilator. Feeling exhausted after 20 mins in the cave.


As the air became more oppressive I only hoped that I would last to tell the tale… could we do this place justice and film the ‘crown jewel’ of our series in just two days? Professor Iain Stewart, our presenter, was arriving tomorrow, and as a fellow geologist I couldn’t wait to hear what he thought. This was going to be the most challenging shoot of my life.

Aborted Relics

Cueva de los Cristales is the incarnation of our most awesome science fiction imaginations — Jules Verne’s Journey to the Centre of the Earth, Superman’s Fortress of Solitude. At about the same time as humans first ventured out of Africa, these crystals began to slowly grow. For half a million years they remained protected and nurtured by a womb of hot hydrothermal fluids rich with minerals.

Undisturbed, one can only guess how big they may have eventually grown. Yet when mining began here over a hundred years ago, the water table was lowered and the cave drained. The crystals’ seemingly interminable development was frozen forever leaving them as aborted relics of the deep Earth. It wasn’t until 2001 that miners, searching for lead, eventually penetrated the cave wall and brought it to light. The very act of discovering and witnessing them has triggered their slow decay and now no one knows what their fate will be. Once the mine ceases to operate it could be flooded by polluted mine water and abandoned forever, and that’s if ambitious mineral sellers don’t get to them first and rip them out to sell around the world — a plight of other smaller crystal caves in the area. My hope is that Gonzalo will prevail in his mission to secure funding and to preserve this site as a world heritage monument. To me they are a testament to the hidden forces of the planet, forces which operate on scales far beyond our own.

Who knows what other wonders lie hidden deep inside the Earth?

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This is me and one of Gonzalo’s team right in the heart of the cave. The furthest and most difficult part to reach is just behind me — it takes 10 minutes just to get there.


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Trying to scramble over the jagged crystals whilst wearing an oversized jump suit stuffed with ice, and a large backpack, is no easy feat — especially when carrying a large professional camera. Photograph by Carsten Peter/Speleoresearch & Films


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It’s such as task to get into the cave that by the time we were in position to film a shot the doctor was calling for us to get back out. Photograph by Carsten Peter/Speleoresearch & Films


Read more about the Crystal Cave and view more images in this special article by National Geographic.

How Earth Changed History: Beneath the Crust will be airing on National Geographic Channel this Sunday, June 20 at 9P et/pt.

Also be sure to tune in for How the Earth Changed History: Water World on Sunday June 20 at 8P et/pt.