Beyond a sprawling army camp 32km north of Lachen, Thanggu (3850m) is essentially a summer herders' settlement with an end-of-the-world feel. A few hardy travellers spend the night here, but most groups just stop for breakfast en route to Gurudongmar Lake (5150m), a memorable sight reflecting its backdrop of snowy peaks in mirror-calm water, at least when it isn't frozen. Chomalu, around 10km further, is India's highest lake. Unfortunately, foreigners are not permitted to visit either lake.
Foreigners usually can wander in the Tsopta Valley though, reached by a boulder-strewn stream some 2km from Thanggu. Just above the tree line, the scenery takes on the added drama of a glacier-toothed mountain wall framing the western horizon. A two-hour hike leads up to a pair of meditation caves, one of which was reputedly used for two years by the famous French traveller and mystic Alexandra David-Neel.