The Karnali River (Grade 4 to 5) in the far west is the longest and largest river in Nepal. To arrive at its banks requires a two-day trek from Surkhet in the Terai. The next 90 kms are spent flying through septacular landscapes and narrow gorges and down some of the most challenging rapids in the world. For the remaining 90 km, the scenery and wildlife are the main attraction, as it the abundance of fish. During most of this trip, the wilderness is uninterrupted by human habitations.