Cueva de los Cristales is one of the most incredible and beautiful places on the planet - it also happens to be one of the deadliest.
'It's 50oC 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.' Read the rest of my account of filming in the cave & see some photos here.
'How Earth Made Us' starts on Tuesday January 19th on BBC Two at 9pm.