Nepal has plenty of amazing mountain rivers and is very famous for high current White water rafting. Nepal has the best places in the world for white water rafting and kayaking. Rivers are graded for difficulty on an international scale from class 1 to 6 with class 1 defined as easy-moving with few obstacles and class 6 is being considered nearly impossible to negotiate and a hazard to life.
People who are in reasonable physical shape and aren't afraid of water they can safely go rafting on with grading from class 1 to 3. For more difficult and exciting class 4 and 5 rivers which require active, confident and have some rafting experiences.