For the experienced hiker, Tibet offers plenty of enticing trekking routes – though you will currently need to negotiate for a guide and a travel agency to endorse your travel permit and accompany you for the entire duration of the trek. The popular Ganden–Samye trek has the advantages that both the start and finish points are relatively accessible from Lhasa and that it takes only three to four days. Also worth considering are treks to the cave hermitage of Drak Yerpa from Lhasa (allow a full day and be prepared to camp), and the five-day trek from Tingri to Everest Base Camp via Rongbuk. More challenging options include: the sixteen-day mammoth trek to the Kangshung face of Everest, exploring the valleys east of the mountain (the trip to second base camp and beyond on the mountain itself should only be tackled by experienced climbers); the 24-day circumnavigation of Namtso Lake, including the arduous exploration of the Shang Valley to the southwest; and the great thirty-day circuit from Lhatse to Lake Dangra up on the Chang Tang plateau.
Spring (April–June) and autumn (Sept–Nov) are the best seasons in which to trek, though cold-weather threats such as hypothermia and frostbite should be taken seriously even in these months. While trekking is possible at any time in the valleys, high altitudes become virtually impossible in the winter; anyone contemplating trekking at this time should be sure to check information about the terrain and likely conditions. During the wettest months (June–Sept), rivers are in flood, and crossing them can be difficult, even impossible. Once you start trekking, you get off the beaten track extremely quickly, and there is no infrastructure to support trekkers and no rescue service; you therefore need to be fit, acclimatized, self-reliant and prepared to do some research before you go. There are two essential books: Tibet Handbook: a Pilgrimage Guide by Victor Chan (Moon), and Trekking in Tibet by Gary McCue (Cordee), which is especially good for shorter day-treks that anyone can do without all the gear.