The K2, as you may or may not know, is the world’s second highest mountain after Everest. At over 8,000 metres high, it represents a huge climbing challenge even in its mildest season, but in winter has never been successfully surmounted. In fact, past attempts have managed no more than 7,650 of the mountain’s 8,611 metres during this tricky season, which throws icy winds, fierce gails, and heavy snow at all who make the attempt. Of the world’s 8 highest mountains, the K2 is the only one never to have been climbed in winter, despite being only 200 metres shorter than Everest.