An international team of scientists explores a Mexican cave filled with ancient, giant crystals. With temperatures near 50 degrees Celsius, and 100 per cent humidity, the crystal cave is one of earth's most stunning but deadliest environments.

Wearing specialized suits built to protect them against the cave's harsh environs, the scientists work to unlock the secrets of the mysterious crystals.

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Interesting Facts about the Crystal Caves:

• The giant crystals found in the caves at Naica are softer than a human fingernail.
• The largest crystal found at Naica is 500,000 years old.
• The stunning crystal pillars are made from the same common mineral as drywall - it's called gypsum.
• The Naica cave's deadly heat comes from the depths of the Earth. Naica sits on a set of fault lines. A magma chamber a mile and a half down warms the water that flows throughout the mountain.
• The Naica principle cave "Cueva de Los Cristales" is 45 degrees Celsius and 100 per cent humidity.
• The Naica facilit
  y pumps 16,000 gallons of water per minute out of the mine and runs 24-7.
• The water pumped from the Naica mine formed a lake in the arid Chihuahua desert and is also used to irrigate a golf course.
• Naica is one of the most productive lead mines in the world, and a huge supplier of the world's silver as well.
• The Naica cave actuality footage was shot on solid-state memory HD video cameras (tape-less) wrapped in plastic bags and pre-heated for three hours prior to entering the cave.
• The Naica Project team created a stop-motion robot and fitted it with a Nikon digital still camera powered by a custom software to capture beauty-shot sequences of the cave with 10-megapixel resolution.