The Hoang Lien Mountains, nicknamed the Tonkinese Apple by the French. These mountains include Fansipan, which at 3143m is Vietnam's highest peak. The summit towers above Sapa, although it is often obscured by clouds and is occasionally dusted with snow. The peak is accessible all year to those in good shape and properly equipped, but don't underestimate the challenge. It is very wet, and can be perilously slippery and generally cold, so you must be prepared. Do not attempt an ascent if the weather is terrible in Sapa, as limited visibility on Fansipan could be treacherous. The summit of Fansipan is 18km from Sapa and can be reached only on foot. The terrain is rough and adverse weather is frequent. 

Despite the short distance, the round trip usually takes 3 or 4 days; some very fit and experienced hikers do it in 2 days, but this is rare. 

After the first morning you won't see any villages: just the forest, striking mountain vistas and perhaps some local wildlife such as monkeys, mountain goats and birds. No ropes or technical climbing skills are needed, just endurance. There are no mountain huts or other facilities along the way (yet), so you need to be self-sufficient. This means taking a sleeping bag, waterproof lent, food, stove, raincoat or poncho, compass and other miscellaneous survival gear. Hiring a reputable guide is vital and, unless you are a seriously experienced mountaineer, finding porters who will carry your gear is also strongly recommended. 

Weather-wise the best time for making the ascent is from mid-October to mid-December, and again in March, when wildflowers are in bloom.

The incredible road between Sapa and Lai Chau crosses the Tram Ton Pass on the northern side of Fansipan, 15km from Sapa. At 1900m this is the highest mountain pass in Vietnam. Even if you are not planning to carry on around the northwest, it is well worth coming up here to experience the incredible views from the top of this pass. Descend by mountain bike before returning by truck or rent a motorbike to make the short hop to the new Tam Duong (Binh Lu). This is a seriously spectacular ride. On the Sapa side of the mountain the weather is often cold. foggy and generally miserable. Drop down a few hundred metres below the pass on the Lai Chau side and it will often be sunny and warm. Ferocious winds come ripping over the pass, which is not surprising given the temperature differences - Sapa is the coldest place in Vietnam while Lai Chau is the warmest. Tram Ton Pass is the dividing line between two great weather fronts - who says you can't see air? 

Alongside the road, about 5km towards Sapa is Tha Bac (the Silver Waterfall). With a height of 100m, it's a big one, and the loop track is steep and scenic.