Yama Do-sotup-chu Valley [ 5-7 hours • 10km • 1000m ascent • 450m descent ]

One hour past Yama Do leave the valley floor and ascend a shelf on the east (left) side of the valley to avoid a steep gully that forms around the stream. In another 45 minutes you enter a wet alpine basin studded with tussock grass. The Shug-la is at least 1 1/4 hours from the basin. Remain on the east side of the valley as it bends to the left. The Shug-la (5250m) cannot be seen until you're virtually on top of it. It is marked by a large cairn covered in prayer flags and yak horns.

The route continues over the Shug-la and descends sharply through a boulder field, losing 200m of elevation. Be on the lookout for a clear trail marked by cairns on the left side of the boulder field. This trail traverses the ridge in a south-easterly direction paralleling the valley below. Retreat down the valley for a bolt hole back to the Lhasa-Ganden Hwy, a long day of walking away.

The trail gradually descends to reach the valley floor, 1 1/2 hours from the pass. Cross the large stream, the Tsotup-chu, which flows through the valley. During heavy summer rains take special care to find a safe ford. The pastures in the area support large herds of yaks, goats and sheep, and during the trekking season herders are often camped here. It is a 2 to 2 1/2 hours walk from the stream ford to the second pass, the Chitu-la.

An alternative route to Samye via the Gampa-la (5050m) follows the main branch of the Tsotup-chu past a couple of lakes to the pass. South of the Gampa-la the trail plunges into a gorge crisscrossing the stream that flows down from it. These fords may pose problems during summer rains or when completely frozen. Camping. B,L,D