"When we first arrived at the Naica mine, Manuel and his crew took us inside without wearing the special cooling suits. This was in order to get us used to what REAL heat is like. There is a steel door protecting the cave and as soon as you pass through it, the temperature hits you like a truck.
But as soon as you get your first glimpse of the incredible crystals, you want to keep going deeper. We were inside for only 14 minutes, which was pushing the danger limits without cooling suits. When we exited, the staging area was a "cool" 41 Celsius. My heart was pounding and I was completely soaked in sweat, my shirts, pants, socks & boots... Everything. All we could do was sit, drink and rest."
Cooling suits - vests of frozen gel packs surrounded by insulation, plus a backpack that supplies the wearer with chilled air to breathe - allow people to remain in the mine for close to an hour. Kourounis and his crew took the opportunity to snap these incredible images as well as shoot some video.
Of his experience visiting the crystal cave, Kourounis writes: