Widely acknowledged as one of the ten best rafting trips in the world, the Sun Koshi is the most popular of several longer floats in Nepal, and logistics are fairly easy, making it one of the cheapest in terms of cost per day. It’s an eight-day run beginning at Dolalghat, three hours east of Kathmandu, and ending at Chatara, between Dharan and the Koshi Tappu Wildlife Refuge in the Eastern Terai. If you’re planning to go on from Nepal to Darjeeling, this raft trip cuts out most of the 20hr bus ride to the eastern border.
Relatively few companies run scheduled trips on the Sun Koshi, so you’re less likely to see other parties, and the camping, on beautiful white-sand beaches, is great. The river traverses a remote part of the country, flowing through a varied landscape of jungle-clad canyons, arid, open valleys and sparse settlements. Unlike most rivers, which start out rough and get tamer as they descend, this one starts gently, affording a chance to build up experience and confidence prior to a steady diet of increasingly exciting whitewater (Class 3–4). This makes it an especially good choice for those doing their first river trip. It’s at its best for rafting at medium to high flows – from mid-September to late October and in May and early June; from December to March much of the whitewater disappears.
Note that the new Sindhulimadi highway alongside the top 30km of the Sun Koshi is almost complete; when it is, it will allow shorter six-day trips on the river (probably with a put-in at Chainpur, a 5hr drive from Kathmandu) and will also probably halve the return time from the take-out.