Lachen is a town in North Sikkim district in the Indian state of Sikkim. It is located at an elevation of 2,750 metres. The name Lachen means "big pass". The town is being promoted as a tourist destination by the Sikkimese government. The town commands a panoramic view of the Himalayan mountains and is abundant in wildlife. The town forms the base to the Chopta Valley and Gurudongmar Lake. An annual yak race, the Thangu is held here in summer.
Lachen is about 129 km from Gangtok, can be reached via road, a six hour adventurous journey from Gangtok. Also a short two day long trekking route connects Yumthang Valley to Lachen.It has population of around 1000. Lachen have its own system to follow rules and regulation and the system is called Dzumsa head of the Dzumsa are known as Pipon & Gyenbos. You can find guest house and homestay to stay easily. While going in north direction you will find an old town of Thangu, in Thangu the daytime temperature is from 4 to 12 degrees Celsius (40 to 55 °F) even in the months of June and July. Gurudongmar Lake can be reached from Lachen, a panoramic, sacred lake in the Great Himalayas Region. The best time to visit Lachen is from November to June.