The river is characteristic of extreme white water and normally cannot be used for watersports. The descent is over 5% and there are rapids that reach WW VI difficulty (not yet rated by
AWA) and places that need to be portaged even with the best equipment. In addition, the river often changes — big stones getting moved around by natural forces etc. Flowing down from Mount Everest, the river is believed to be the highest navigable
whitewater. As such, it came to the attention of teams participating in the world cup since
Austrian paddlers made a world record descending from 3,200 m altitude in
France.
Czechoslovak sportsmen then agreed to take up the challenge. A team of sixteen men, including fourteen Czechs and two Slovaks, had been gathered and on 4 January 1973 they set on the journey from
Děhylov by cars (notably using customized
Tatra 138 that had to survive over 30,000 km forth and back). For the last part from
Lukla to
Pheriche, 110
porters were hired to carry the boats and other equipment. The actual river trip began on 1 April near Pheriche at 4,243
mamsl and ran for 126 km down to Sun Kosi. The paddlers used both covered tandem canoes (
C2) of Vertex brand and solo
kayaks (K1), all made of
fiberglass. The expedition returned home safely in August the same year. Three years later, in 1976, there was a British expedition of seven kayakers under the leadership of
Mike Jones. They used 4 metres long fiberglass slalom-style kayaks specially designed by Pyranha Canoes with extra buoyancy and reinforcement. The expedition is notable for taking place in September to avoid ice and when the water was high to set new altitude record. They paddled at approximately 5300 mamsl on one of the lakes at the
Khumbu Glacier. But the high water flow had its downside — many parts were too dangerous and had to be omitted; the result was that just two boats out of eleven survived to the end at the confluence with Sun Kosi. It is unclear which parts of the river were skipped, but the descent is generally considered incomplete. The next year,
HTV documentary movie "Dudh Kosi: Relentless River of Everest" was released which is a source of common misconception that this was the first trip on the river. Note that both expeditions didn't embark on Dudh Kosi but rather on Lobuche which is the river formed by the Khumbu Glacier and which runs around Pheriche. Just below Pheriche it merges with
Imja Khola which then runs for about ten kilometres before it joins Dudh Kosi under
Tengboche. Since then, there were many expeditions using wide variety of boat constructions allowing to run some rapids that had to be portaged previously. However the access to upper parts above Lukla is now limited due to stricter regulations in and around national parks. ==References==