Bauer's spur
With Nepal closed, pre-war Kangchenjunga expeditions came up the Zemu Glacier. Paul Bauer's Germans tried the northeast spur in 1929 and 1931, and reached 7,400 m in 1929.
After the trail · the almanac
The trek in four numbers
A long, remote walk in a restricted area, to the foot of the world's third-highest mountain.
4,935m
Green Lake
92km
Out and back, 12 days
~26km
Zemu Glacier
8,586m
Kangchenjunga
💪 Difficult🌸 Apr–May🍂 Oct–Nov🪪 Restricted area
Day by day
Twelve days, step by step
This is the 16-day plan of Trekking in Sikkim and Adarsh Tours, with 12 days on foot and two rest days. Himalaya Shelter and Far Out Trek do it in 9–10 walking days.
How high you are on each kilometre
- Day 2Gangtok → Lachen135 km by road6–7 h🛏️ Lachen · 2,730 m
- Day 3Lachen → TalemUp the Zemu Chu12 km · 5–6 h⛺ Tents · 3,240 m
- Day 4Talem → JakthangForest and waterfalls12 km · 5–6 h⛺ Tents · 3,430 m
- Day 5JakthangRest and acclimatise—⛺ Tents · 3,430 m
- Day 6Jakthang → YabukTo the glacier8 km · 4–5 h⛺ Tents · 4,040 m
- Day 7Yabuk → Rest CampAlong the moraine8 km · 3–4 h⛺ Tents · 4,725 m
- Day 8Rest Camp → Green LakeUnder Kangchenjunga6 km · 3–4 h⛺ Tents · 4,935 m
- Day 9Green LakeRest day—⛺ Tents · 4,935 m
- Days 10–14Green Lake → LachenThe same way down46 km over 5 days🛏️ Lachen
Stories and nature
Climbers, a yeti and a lost lake
Tombazi's yeti
In 1925 N. A. Tombazi reported an upright, human-like figure at about 4,600 m near the Zemu Glacier. He watched it for about a minute.
The vanished lake
The Zemu is about 26 km long. Green Lake, once fed by it, has drained away: Harish Kapadia found it gone in 1976.
October 2023
A flash flood from South Lhonak Lake tore down the Teesta, destroying roads, bridges and the Chungthang dam. Lachen was shut to tourists for almost three years.
When to go
Spring and autumn
Operators run it in April–May and October–November. Himalaya Shelter also lists March, June and September.
April–May
Spring. Rhododendrons bloom in the lower forest.
June–September
Monsoon. Heavy rain can close North Sikkim's roads at short notice.
October–November
The second season, after the monsoon.
December–February
Not offered by the operators we found.
Plan your trip
Getting to Lachen
Fly to Bagdogra or take the train to New Jalpaiguri, then drive via Gangtok.
- Bagdogra🚙 About 124 km to Gangtok, 5 h
- Gangtok🚙 135 km to Lachen, 6–7 h
- Lachen🥾 92 km out and back, 12 days
Since September 2026, vehicles must cross the Toong check-post by 4 pm in both directions, so leave Gangtok early.
Cost
Himalaya Shelter charges ₹78,000 + 5% GST from NJP. Glacier Treks quotes ₹1,70,000 for Indians and $2,500 for foreigners.
Permits
A restricted-area permit from Sikkim's Home Department, through a registered Sikkim agency, for groups of two or more. Allow months.
2026 status
Lachen reopened to tourists on 11 September 2026. We found no operator with confirmed dates for this trek since the 2023 flood. Ask a Gangtok agency.
Altitude
You sleep at 4,725 m and 4,935 m. The plan has rest days at Jakthang and Green Lake.
For foreign trekkers
What's different for you
Foreigners need a Sikkim entry permit and a restricted-area trek permit, arranged by a registered Sikkim agency for groups of two or more, and usually pay more. Rules change: confirm with the issuing office before you travel. Checked October 2026.
Sikkim entry permit
Foreigners need a Sikkim Inner Line Permit, valid for 30 days. Get it at Sikkim House in Delhi or Kolkata, or at the Rangpo and Melli check-posts. Far Out Trek
Restricted-area trek permit
Green Lake is a restricted area. The trek permit comes from Sikkim's Home Department, only through a registered Sikkim agency, for at least two people. You need passport and visa copies, four photos and a signed permit form. Far Out Trek
Higher prices
Glacier Treks charges foreigners $2,500 against ₹1,70,000 for Indians. Himalaya Shelter adds extra forest charges for international trekkers. Glacier Treks
Carry your passport
Keep your passport on you at all times in North Sikkim. Adarsh Tours
Good to know
The small things
Cash, signal, water, permits and help on the way. Checked October 2026; confirm with your operator.
Lachen has just reopened
Lachen was closed to tourists after the October 2023 flood. Permits resumed on 11 September 2026, but landslides can still close the road. ETV Bharat
Cross Toong by 4 pm
Tourist vehicles to and from Lachen must cross the Toong check-post by 4 pm. Leave Gangtok early. Livetraveller
Permits take time
The restricted-area permit comes from Sikkim's Home Department, only through a registered agency, for groups of two or more. Organising it can take months. Walkopedia
Drinking water
Spring water is generally safe, but carry purifying tablets. The camp cooks also give boiled water. Far Out Trek
Food
Hot vegetarian meals: porridge, pancakes, noodle soup, chowmein, fried rice and dal. Far Out Trek
Tents and toilets
Twin-share tents with sleeping mats, plus kitchen, dining and toilet tents. Far Out Trek
Offloading
Himalaya Shelter carries a personal bag for ₹500 a day, up to 12 kg. Himalaya Shelter
Getting to Lachen
Bagdogra to Gangtok is about 124 km (5 h). Gangtok to Lachen is 135 km (6–7 h). Trekking in Sikkim
Budget for delays
Landslides or strikes can hold you up, and any extra hotel nights or transport are at your cost. Adarsh Tours
What to pack
Your checklist
Tick items as you pack. Your ticks stay saved on this device.
Clothing
Shoes
Gear
Papers and money
Health
List from Himalaya Shelter: things to carry.
Who runs it
Choose an operator
We found 5 operators with a Green Lake page in October 2026. None lists a dated departure: Lachen only reopened to tourists on 11 September 2026 after the 2023 flood.
Prices are base prices from each operator's own page (October 2026); most add 5% GST. Ratings are what each operator shows, not an independent audit. Names marked † show last season's price or one seen only in a search snippet.