Lachung is at the confluence of the Lachen and Lachung Rivers, both of which are tributaries of the Teesta. It is approximately 9,600 feet (2,900 meters) above sea level.
It serves as the Indian Army's forward base. Tourists movement in this town can be visible from October to May. During winter the town is generally shrouded in snow. Additionally, Lachung serves as the starting point for the Rhododendron Valley Trek, which travels from Yumthang Valley to Lachen Valley.