The Lamkhaga Pass (5282 mts/17320 ft) is one of the toughest pass which connects Kinnour district of Himachal Pradesh with Harshil in Uttrakhand. The Lamkhaga Pass trek starts from Chitkul the last Village of sangla valley in Himachal, though it can be done from Harshil side also. This trek is a fairly remote trek, which was first crossed by Greek-British author and mountaineer Marco Alexander Pallis in 1933.
References
Lamkhaga Pass Wikipedia(Text) CC BY-SA