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.