Zemu Gap from South

The First Documented Ascent

Anindya Mukherjee

The history of exploration around Kangchenjunga1, especially around its south, southeast and east flanks has always fascinated me. The classic journeys and adventures of pioneers like W.W. Graham, John Claude White, Douglas Freshfield, Dr. A.M. Kellas, Harold Raeburn, N.A. Tombazi, Lord John Hunt and Paul Bauer ignited my imagination. Final inspiration came from reading my hero H.W. Tilman’s account in the Himalayan Journal (Vol. IX) on his attempt on Zemu Gap from south in 1936.

The primary challenge of climbing Zemu Gap from the south has always been its remote and complicated approach. Many have failed to reach even the foot of this col. To add to that its apparently impregnable defenses took Zemu Gap to a next level of exploratory climbing. In 1925, Greek photographer N.A. Tombazi is said to have made its first ascent from south; but he did not take any photographs! To me and my long time expedition partner Thendup Sherpa; all the above factors seemed highly intriguing and certainly worth investigating.

From the south summit of Kangchenjunga (8476 m) a high ridge extends east separating the Zemu glacier valley on the north from Tongshyong and Talung glaciers to the south. On this ridge, between Zemu peak (7730 m), Unnamed peak (7038 m) and Simvu Twins (6812 m & 6811 m) there is a sudden drop in altitude to form a col. At 5861 m this col is popularly known as the Zemu Gap2. To its north is Zemu glacier and to its south Tongshyong glacier. Its coordinates are 27°40’9”N 88°12’53”E. From Zemu Gap a small, steep glacier flows down to Tongshyong as a tributary glacier. To climb Zemu Gap from Tongshyong, one would have to first negotiate two icefalls on this tributary glacier and then find a route on the head wall. But before the climbing problem comes the approach issue. Approaching Zemu Gap from north is straightforward.

Talung (7349 m) and its south ridge leading to Kabru North. (Anindya Mukherjee)

Talung (7349 m) and its south ridge leading to Kabru North. (Anindya Mukherjee)

From south, one has to cross Guicha la from the Prek chu valley, across Talung glacier, climb onto Tongshyong glacier by Tilman’s ‘snow col’ and then arrive at the foot of the tributary glacier. Another way of reaching Tongshyong could be to reach its snout (either from Guicha la-Talung route or through the Rukel-Rongyoung gorge route) and then traverse towards its head to reach the base of the tributary glacier from Zemu Gap. In 1975, an Indian team (A.J.S. Grewal) found the first option exhausting. They did reach Tongshyong and the base of Zemu Gap’s glacier though. In 2008 and 2010 respectively, a British team and another Indian team failed even to reach Tongshyong by the first option. I somehow preferred the second alternative. Since I had survived the ‘trackless vale of tears’ (Tilman, When Men and Mountains Meet), the Rukel-Rongyoung gorge route in March 2011; I had planned for a direct approach to Tongshyong from Mangan via the gorge route.


Though Sikkim is reasonably accessible, only some half-dozen of its countless lofty peaks have been conquered, and many of its fascinating valleys and uplands have scarcely been trodden by Europeans. There is therefore plenty of scope for explorers and naturalists as well as for climbers. … Nevertheless he is a bold man who, reading of these determined assaults, sometimes successful, sometimes splendid failures, will pronounce the summit of any peak in the Sikkim Himalaya to be definitely inaccessible.

Base camp with Pandim in the background. (Anindya Mukherjee)

Base camp with Pandim in the background. (Anindya Mukherjee)

‘Exploration and Climbing in the Sikkim Himalaya’ Lt. Col. H. W. Tobin, the Himalayan Journal Vol. II.

Albeit, more than 80 years have passed since H.W. Tobin wrote the above lines, some part of Sikkim Himalaya has managed to retain its original flavour! While the factor of inaccessibility has reasonably abated over the past decades; a whole new hurdle has entered the arena. Bureaucracy! The Talung basin3 (which falls partly within the Kangchenjunga National Park and partly in the north Sikkim Lepcha sanctuary called ‘Dzongu’) area is a classic example. Even though this valley system has no proximity or direct access to the Indian-Tibet border; it remains veiled behind restrictions and a mountain of paper work.

In 2008, a British team got permission to cross Zemu Gap from the south and traverse the Zemu glacier valley down to Lachen. This was particularly encouraging news for Thendup Sherpa and me. With my friend O.T. Lepcha’s involvement and active support we also succeeded in procuring the necessary permits. This resulted in a series of expeditions that I would undertake in 2011.

To start the exploration process, we repeated Claude White’s route of July 1890, in reverse, forcing up the Rongyoung-Rukel chu gorges to connect Mangan, north Sikkim with Yoksum, west Sikkim in March 20114. This success reinforced our confidence and we were ready to have an attempt on Zemu Gap from south, a long standing problem in mountaineering history around Kangchenjunga. In November 2011, we crossed Guicha la, went down Talung glacier to set up a high camp on Tongshyong. But a five day long snow storm stopped us from approaching Zemu Gap. We went down the Rukel-Rongyong gorges to Mangan. Finally in December 2011, we were successful in climbing Zemu Gap from Tongshyong glacier, i.e. south.

Zemu Gap and the Talung Basin: Exploration, Attempts and Ascents
Before going into the description of our expedition let us browse through some mountaineering and exploration history of the Talung basin and Zemu Gap.

  1. In 1890, John Claude White, made one of his first expeditions that involved crossing the Guicha la. He crossed Guicha la, went down to Talung glacier (which he referred to as the ‘Kangchen’ glacier - source: Sikhim and Bhutan - Twenty-One years on the North East Frontier 1887-1908 - J. Claude White, p. 57) and then followed the ‘Talung’/‘Ronggyaong’ chu (‘Rungnu’- as per White) eastwards to Sakyong and finally to Ringen (the present day location of North Sikkim Government offices above Mangan). In his book he writes on page 53 - In 1890 I made one of my first expeditions to the snows, crossing the Giucha-la pass and from there making my way to Ringen, following a route the latter part of which had certainly never been traversed by a European, and I doubt by anyone, except possibly a very occasional Lepcha.
    H.W. Tilman later called this gorge route ‘the trackless vale of tears’ in his book When Men and Mountains Meet. (p.321). Lepchas of the Dzongu valley call Talung chu as Ronggyaong or Rongyoung chu. In this report we have referred to it as Rongyoung.
  2. In 1899, Douglas Freshfield, accompanied by Professor Garwood intended to determine practicability of an ascent to Zemu Gap by its northern approaches (Zemu glacier). Bad weather prevented them from making much progress beyond Green Lake. Rinzin Namgyal and Sella brothers were also part of his high level tour. (Round Kanchenjunga by Douglas Freshfield)
  3. Dr. A. Kellas with three porters camped at 18,200 ft, just below Zemu Gap and then went to the col on the morning of 12 May 1910. ‘The slope fell away steeply in front, and a few yards down there was a crevasse that stretched right across the gully.’ (‘The Mountains of Northern India and Sikkim’, the Alpine Journal 26 (1912), Pp. 113-142 - A.M. Kellas). This is probably the first documented ascent of Zemu Gap from north; i.e. Zemu glacier.
  4. Narsing (5825 m) and its satellite peak (5188 m). (Anindya Mukherjee)

    Narsing (5825 m) and its satellite peak (5188 m). (Anindya Mukherjee)

  5. Zemu Gap from Camp 3. (Anindya Mukherjee)Zemu Gap from Camp 3. (Anindya Mukherjee)1920 - First attempt on Zemu Gap from south; i.e. Tongshyong glacier - H.W. Tobin and Harold Raeburn, explored Talung and Tongshyong glaciers and attempted to ascend Zemu Gap from south. He describes the approach to the Zemu Gap from the Tongshyong glacier as ‘the narrow entrance and the mountain sides raked with such a continuous hail of rocks and debris that an approach by this route would have been little short of suicidal’… On their way out of Talung basin they took Claude White’s route of 1890 following the gorges of Rukel and Rongyoung rivers. (‘Exploration and Climbing in the Sikkim Himalaya’, the Himalayan Journal Vol. II, 1930, Pp. 1-12).
  6. N.A. Tombazi made a tour of the locality in 1925 (The Alpine Journal Vol. 38 p. 150, the Geographical Journal Vol. 67). He claimed to have made the first ascent to the Zemu Gap from the south. He however provided no photographic evidence on his claimed ascent.
  7. In 1926, Captain Boustead declared he reached the Zemu Gap from the south. (The Geographical Journal, Vol. 69, Pp. 344-350). But his description raised suspicions in H.W. Tilman’s mind and in 1936 during his attempt from south; HWT suggested Captain Boustead may have mistaken a col located at the head of Tongshyong glacier as Zemu Gap. In Tilman’s words, ‘… the Zemu Gap differed so widely from the account I had read that I half believed a mistake had been made and that the genuine gap lay concealed behind some corner near the head of the Tongshyong. There was, however, no other break in the mighty south-east ridge of Kangchenjunga, and the low, easy col at the head of the glacier obviously led over into the wide bay at the head of the Talung. Is it possible that, in the thick weather prevailing when Captain Boustead was here, this had been mistaken for the Zemu Gap?’ (‘The Zemu Gap’, HJ Vol. IX, H.W. Tilman)
  8. Head wall of Zemu Gap from south. (Anindya Mukherjee)Head wall of Zemu Gap from south. (Anindya Mukherjee)Karl von Kraus, Joachim Leupold of the German expedition to Kangchenjunga (led by Paul Bauer) climbed Zemu Gap in July-August 1929 from north, Zemu glacier. This was the second ascent from north.
  9. H.W. Tilman, made his first attempt on Zemu Gap, from the south in 1936 accompanied by Pasang Kikuli. Tilman reached Tongshyong glacier from Talung by crossing a ‘snow col’.

    (This col is located between Talung and Tongshyong glaciers on the ridge running west to east separating the two glaciers in the process). In Tilman’s words, ‘Although we were loath to give imminent, for beyond these obstacles lay the final ice-wall which from below appeared impregnable.’ He was thwarted ‘where we had a good view of the final wall. It was as high as we had feared, all iced, and appeared to overhang in places.’ On his way out he followed Claude White (1890) and Harold Raeburn (1920)’s direction down the Ruykel- Rongyoung chu gorges to Sanklan Sampo below Mangan. (When Men and Mountains Meet, p. 311)
  10. Zemu Gap in 1937 and in 2011.

    Zemu Gap in 1937 and in 2011.

  11. In 1937, during a winter expedition lasting nearly two months, John Hunt and Pasang Kikuli reached the Zemu Gap from the north on 18 November. Evidence showed that the German party had already been there earlier (Led by Paul Bauer, and three other climbers, Adolf Gottner, Dr. Giinter Hepp, and Dr. Karl Wien were climbing Siniolchu and Simvu North peaks in September - October 1937). Therefore, Paul Bauer’s party may have made the 3rd ascent of Zemu Gap from north and Lord Hunt’s team the 4th. (‘A winter visit to the Zemu Glacier’, by John Hunt, the Himalayan Journal Vol. X (1938) and – ‘Ascent of Siniolchu and Simvu North Peak I’ by Dr. Karl Wien, HJ Vol. IX)
  12. H.W. Tilman made a second attempt to cross Zemu Gap from the north in July 1938. He was successful on 9 July, though the descent down the steep southern side was fraught with difficulties. On his way out he avoided using the direct route down to Talung glacier by the snow col, followed Tongshyong glacier downhill to climb up Talung glacier and crossed the higher Guicha la into Prek chu valley. This was the fifth ascent from north and the only successful crossing of Zemu Gap.
  13. In 1975, J.K. Bajaj, Nima Tashi and Sherpa Passang after their failed attempt on Talung peak investigated the Zemu Gap from the Tongshyong glacier. They were prevented from crossing the Gap ‘by two big open crevasses approx. 40 ft in width’ just 200 ft short of the col. ‘...it is clear that the Gap can be reached if one goes prepared to bridge the two crevasses.’ (‘Talung 1975,’ A. J. S. Grewal, the Himalayan Journal Vol. 34 (1974-75), Pp. 39-47).
  14. In 2008, an attempt was made by a British team to link together two treks – the Guicha la trek and the Green Lake trek, across Zemu Gap. They crossed Guicha la from the Prek chu valley and reached Talung glacier. Their plan was to reach Tongshyong glacier through the snow col and climb Zemu Gap from south. Their journey ended on the steep (mixed terrain with grass, juniper and scree) slope on the south of the snow col 200 m below the level of Tongshyong glacier. The expedition members were Adrian O’Connor from Leicester, and Colin Knowles and Jerzy Wieczorek from Bristol, all of whom are members of the Red Rope Club.
  15. Approach to Zemu Gap from the Rongyoung-Rukel chu gorges.

    Approach to Zemu Gap from the Rongyoung-Rukel chu gorges.

  16. In 2010, a group from Kolkata (Subhamoy Ghosh), India intended to follow the 2008 British expedition route. They crossed Guicha la from Prek chu valley and reached up to the grass, juniper, scree slope that leads to Tongshyong glacier via Tilman’s snow col.
  17. In March 2011, Thendup Sherpa and Anindya Mukherjee did Claude White’s 1890 route in reverse. It took them 12 days to reach Yoksum in West Sikkim from Mangan in North Sikkim. It was the first ever upstream journey documented up the deep gorges of Rukel-Rongyoung rivers.
  18. In November 2011, Anindya Mukherjee, Arjun Saha, Arindam Sarkar, Thendup Sherpa crossed Guicha la and reached the confluence of Talung chu and Tongshyong chu. Making a base near the confluence they entered Tongshyong glacier traversing from its snout. Their intention to proceed further towards the head of Tongshyong glacier and thereafter to Zemu Gap was foiled by five days of snow storm. They escaped the valley by following Claude White’s route to Sanklan Sampo and Mangan in five days.

Our Journey through the Rongyoung-Rukel gorges and ascent of Zemu Gap from south (3-19 December 2011) Approach through ‘the trackless vale of tears’

Our team gathered in the North Sikkim district head quarters of Mangan on 3 December 2011. Next morning we shopped for groceries, vegetables and other essential commodities for our expedition. Later in the day, we took a jeep to the village of 6th Mile. Next morning we trekked past the village of Lingzya and crossed the Rongyoung river. The September earthquake has devastated the lower Dzongu valley. The village of Be in the Ringi chu catchment has been nearly erased with many dead. Fortunately for us the bridge on the river Rongyoung survived though twisted. We spent that night in a village hut in Sakyong.

On the tributary glacier emanating from Zemu Gap. (Anindya Mukherjee)

On the tributary glacier emanating from Zemu Gap. (Anindya Mukherjee)

Sakyong is the last human habitation on the western edges of Dzongu. Beyond this is the Kangchenjunga National Park. On 6 December 2011, we followed the right bank of Rongyoung. After Singnok we crossed the river over a make shift log bridge. Singnok is a place where Sakyong folks have been cultivating large cardamom for generations. This is mentioned in Claude White’s descriptions.

After crossing the Rongyoung river beyond Singnok, the trail ends and Tilman‘s ‘trackless vale of tears’ begins! We bivouacked below an overhang rock near a beautiful waterfall. It took us around six hours from Sakyong village to reach this spot. We had camped here earlier, in November 2011, while coming down the gorge after our first failed attempt on Zemu Gap from Tongshyong glacier. Next day we kept on the true left of the river and after seven hours, found a cave suitable to spend the night. We could see signs of Himalayan Thars. They certainly have been using this cave as their shelter. We felt like trespassers.

8 December, we left the Rongyoung and followed Rukel river by its left. We camped by the river next to a spectacular gorge formation.

At dusk we were visited by a Himalayan Black Bear. We had to light a fire to drive him away. On 9 December, we reached the junction of streams coming from Tongshyong and Talung glaciers. We established our base camp for Zemu Gap there at 3740 m. Snowfall started in the afternoon and did not stop for the next 30 hours. As a result we lost one day. We had plans to recce and ferry some loads that day into Tongshyong glacier.

11 December saw us moving up the Tongshyong stream and climbing scree to reach the left lateral moraine of Tongshyong glacier. In spite of poor visibility we made good progress and made Camp 1 at 4701 m. Poor visibility and intermittent snowfall continued overnight and the next day. It was difficult to take bearings on our maps and orient ourselves. Due to poor visibility, on 12 December we made an early camp. This was Camp 2 (4968 m).

On 13 December, the sky finally cleared and we realised that we were still far away from the small tributary glacier of Zemu Gap. This small tributary glacier meets Tongshyong near its head. We did a recce and load ferry and in the process had a good view of our objective.

Our observations revealed that there are two icefalls and one final head wall guarding Zemu Gap from any assault from Tongshyong. While the first icefall could be avoided by taking a scree gully on its true right; the second icefall has to be negotiated head on. Not much could be seen of the final head wall. With mixed feelings of hope and despair we came back to Camp 2.

On 14 December, we established Camp 3 above the first icefall, at 5250 m. From here we had good views of the second icefall. Thendup did a further recce that afternoon and returned optimistic. The weather seemed to be stable finally and we had a great view all around. We felt special to be in a place where very few have reached.

15 December, Thendup Sherpa, Anindya Mukherjee and Pemba Sherpa left Camp 3 at 5.15 a.m. It took them six hours to negotiate and climb the second icefall (250 m) and 200 m of the final head wall. The headwall was climbed by a rock route avoiding the overhanging blue ice that dominates the centre of the Gap. Standing on Zemu Gap, we felt very satisfied. We could see the upper Zemu glacier to our north, the junction of Twins glacier and Zemu glacier, Sugarloaf (6459 m) and surrounding mountains. To our east and ENE we could see the Simvu massif and its northern aspects. The summit of 6812 m (one of the Simvu twins) and peak 6587 m were also distinct. To our west a steep slope with threatening seracs climbed towards peak 7038 m. To our SSE we saw peak 6350 m (located at the head of South Simvu glacier) and to our south Pandim (6691 m), Tilman’s ‘snow col’ separating Talung and Tongshyong glaciers, Guicha la (4940 m), and peak 5962 m were noted. We took photographs and started to retrace our steps down. After many short pitches of down climbing and five abseils on rock and ice we were at the bottom of the second icefall and in relative safe zone. Next day, 16 December, we trekked down to our base. It took us three days to retrace our steps through the gorge and reach 6th Mile village and Mangan.

Team: Thendup Sherpa, Anindya Mukherjee, Pemba Sherpa, Phurtemba Sherpa, Gyalzen Sherpa.

First ‘documented’ ascent of Zemu Gap from the south achieved by an Indian team in December 2011.


  1. The spelling of ‘Kangchenjunga’ has long been debated. For wider reference to the etymology consult the Himalayan Journal Vol. IV, p. 198-214.
  2. Also referred to as ‘Zemu la’ and ‘Cloud Gap’ in some journals.
  3. Mostly referred to as Rukel - Rongyoung chu gorges in this report.
  4. See ‘The Land of Mythical Paradise’, HJ Vol. 67, p. 30.


This expedition won the first ‘Jagdish Nanavati Award for Excellence in Mountaineering’ in 2013 instituted by the Himalayan Club. (Ed.)


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