Gurudongmar is a lake at 5,430 metres in the far north of Sikkim, close to the Tibetan border, and for half the year it freezes solid except for one corner. The ice holds from November into the middle of May. The story goes that Guru Padmasambhava, who carried Buddhism into Tibet in the eighth century, came through and found the water locked and the people with nothing to drink. He blessed a single stretch of shallows, and it has stayed open through every winter since. The lake carries his name, and the water is held to heal. Pilgrims go down to that corner, cup it in their hands and drink, then fill a bottle to carry home the way Hindus carry water from the Ganges. Childless couples come to drink there and pray for a child. In 1997 an Indian Army unit raised a Gurdwara on the shore, sure that Guru Nanak had blessed the same water on his own travels. Buddhists in the valley said the site belonged to Padmasambhava's tradition, and in 2001 the building was handed to Lachen Monastery.
The road comes up from Lachen, the last village, onto a plateau where nothing grows. Not everyone gets to the shore. It sits inside a restricted border zone, and the permit is issued only to Indian citizens, so foreign visitors are turned back at Thangu. In the first hour after sunrise the surface still holds the Kangchengyao massif upside down, the wind has not started, and sound almost disappears. Faint yak trails run off along the bare, snow-flecked edge, and a few minutes of walking puts the small crowd behind you. The plateau opens out brown and empty, with yak and blue sheep grazing the high pastures, and the water below the glaciers is a hard turquoise, the only colour you will see up here. Then the first gust crosses the lake, and your headache sharpens as the day warms. By late morning the jeeps are turning back down the mountain, and the lake is going with them, a litre at a time, in the bottles on the floor.