Semo La is a high mountain pass at an elevation of 5.578m (18,300ft) above the sea level, located in Tsochen county in Ngari Prefecture, in the central part of Tibet, in China. It gives access to the Chang Tang region. It’s one of the highest mountain roads of the country. Most people feel altitude sickness at around 2,500-2,800 meters. Near the pass, oxygen is in short supply.
The climb to the pass, also known as Sangmu La, is simply terrible, with a notorius lack of oxygen that tests the organisms and a high degree of steepness. Travellers use this route as an alternative access route to western Tibet and Mount Kailash, especially when mud makes access by the more southern route difficult.
It has a well-deserved reputation for being dangerous because of unpredictable snowstorms and blizzards, and driving under these conditions, can be extremely challenging. The road crossing the pass is an old unsurfaced track travelled only by a weekly bus and trucks heading west to avoid the boggy parts of the south of the country.
The road to the summit is called 206 Provincial Road (S206), a lonely road in the middle of nowhere. It stays for a long time very high (150km over 5000m above the sea level) over a long high plateau. The bigger problem than the condition of the road is extremely low oxygen for engine combustion.
The unpaved sections of the road can be impassable when wet. After rain, sections of road can become decidedly hazardous when fast-flowing creek crossings and slippery mud can cause road closures. At 5,565 metres it's one of the highest vehicle-accessible pass in the world. It is the highest that has been measured accurately. The bigger problem than the condition of the road is extremely low oxygen for engine combustion.