Killian Fox is an acclaimed music, film and travel writer. He recently wrote this article for the National’s M Magazine.

Chadar Trek, Zanskar, Ladakh in January

Winter is the time of year when visitors to India tend to retreat to the warmer south, steering well clear of the himalayas. Not so the few hardy trekkers who embark each January on the Chadar Trek along the frozen Zanskar River. The Zanskar is one of the oldest inhabited regions of the world, with stark, spectacular valleys and peaks rising to more than 7000 meters. In winter the river is covered with a blanket of ice – chadar in Hindi – and becomes the only viable passage through the snowbound region. Local merchants have been walking it for centuries and now adventure travellers are discovering the rewards of undertaking this daunting 14-day, 140km march.

The downsides? Minus 30 degree nights, thin ice and the risk of frostbite or worse. The upsides? Glimpsing ibexes, dipper birds and, if you are really lucky, the elusive snow leopard; getting an insight into a fascinating ancient culture divorced form modern life; visiting Buddhist monasteries built into cliffs; basking in the awesome beauty of the landscape. And, of course, after it’s all over, having the satisfaction of completeing one of the world’s most challenging treks.

A 20 day trek with India Beat (www.indiabeat.co.uk; 0091 141 6519797) costs £1500 based on two people traveling, not including sleeping bags or trekking shoes.