Nathu La is a mountain pass on the border between Sikkim and Tibet, at 4,310 metres, and it carries more history than its modest size suggests. It was part of an old trade route that linked Lhasa with the plains of Bengal, one of the tributaries of what people now loosely call the Silk Route, along which wool, salt, tea and silver moved by mule. The pass closed after the 1962 war between India and China and stayed shut for decades. It reopened for border trade in 2006, and today the two armies stand a few metres apart on either side of a fence.
Getting here is not like arriving at most passes. Access is controlled, and a permit is required that has to be arranged in Gangtok. The pass is open only on certain days, and regulations about who can go change, so check locally. Foreign nationals have often been barred from this stretch, and visitors are in practice accompanied by registered vehicles. The road itself, from Gangtok, climbs in a long series of hairpins through forest and then bare alpine ground, and it is a serious mountain road: narrow, sometimes broken by landslides in monsoon, and often wrapped in cloud.
The altitude makes its own demands. At more than four thousand metres, you can feel your pulse and your breath, and if you are not acclimatised a quick dash from Gangtok can bring headaches or nausea. Move slowly, drink water, and do not stay long if you feel unwell. The weather can switch from bright sun to freezing fog in minutes, and snow can fall in any month except high summer. In winter the road can be shut entirely.
On the way up you pass Tsomgo Lake, a glacial lake that freezes in winter and draws crowds in season, and the Baba Mandir, a shrine to a soldier remembered as a protector of the road. These are the practical rest points, with tea stalls, hot snacks and a few souvenir shops, and the army maintains a presence along the whole route.
Gangtok, about twenty-three kilometres away, is the only sensible place to fill up, and you should do it before leaving. Carry warm clothes, gloves and something to eat. The silence at the top, apart from the wind and the flags, is quite memorable, and the view across to the Tibetan plateau is the thing you will remember.