This is a high altitude strenuous trekking region which will take you above 4,954 m. Trekking days varies from 8 days to 12 days and regarded as harder.

The time for acquiring Trekking Permit requires more than clear 90 days from Sikkim Govt. as well as Ministry of Home Affairs and Defence at Delhi and Gangtok after submission at Gangtok Office of your Signed application form along with p.p. size photo, bio-data, undertaking, Xerox copy of passport, Indian visa, Sikkim Inner line Permit through your Tour Operator.

This trekking route is designed to take you through ZEMU glacier till the Base Camp of many Highest Mountain Peaks of the region ; GREEN LAKE from Lachenpa Village. One has to trek around 4-5 hrs. a day, the altitude varing from Lachen- 2,726 m. to Green Lake- 4,954 m. making overnight stay at Jakthang-3,429 m, Yabuk- 3,978 m, RestCamp-4,570 m passing through amidst Rhododendron forest and flocks of Blue sheep, high altitude birds, Red Panda and many others.Return trek is through the same route.

This trek from Lachen to Green Lake at the base of Mt. Khangchendzonga in Zemu glacier in North Sikkim, is excellent for the close - up views of the Mt. Siniolchu, and Mt. Simvo . The views of the mountain peaks of the Northern ranges of Khangchendzonga from Green Lake the last point if the excellent and rare.