Sungai Asahan is according to professional rafters one of the best rivers for white water sports in the world and maybe the most beautiful of them all. Asahan is a tough rafting river. The dams of PT. Inalum make the water flow constant, app. 100-130 cubic meters per second. The part used for rafting have been graded to 3-4. the other parts are very dangerous. Rivers are normally graded on a scale from 1-6 where grade 1 is moving water and grade 6 is extremely high risk. Grade 4 is the highest acceptable for commercial rafting. The Asahan river was discovered as a rafting river in the beginning of the 1990ies, however not yet known by many. Asahan is a firsty class river for experienced kayakckers, but maybe too wild for commercial kayaking.

Sungai Asahan is very big and flows fast. The rafting area starts three kilometers above teh bridge in Parhitean. This bridge is called "The Zero Point". The rafting ends in Bandar Pulau over 30 kilometes downstream. The scenery in itself is well worth the money. The partly flows through narrow canyon where small streams fall into the main river. The jungles along the river are rich in wildlife and if you are lucky you will Siamang and other monkeys, Hornbills, Rusa deer, Barking deer and wild boar. Locals claim that there even are a few tigers in the forest. Some kilometers below Hula-huli the river goes through a very steep and narrow canyon., the so-called "Honeymoon Canyon". There is a powerful drop in this canyon. "he Honeymoon Canyon", making commercial runs through it impossible.

There are three alternative stretches for rafting. The first part, called "The Upper Run", starts below the dam of the Inalum plant and ends at the bridge in Parhitean, 3 km down-river. It is a 20 minutes continuous white water stretch graded 4-5. It is not recommended for others than advanced to expert paddlers. The second part, called "The Hula-huli Run", starts at the bridge and goes down to Hula-huli 2 km downstream. It takes 20 minutes. It is graded 3-4. The third stretch, called "The Lower Run" starts in the end of the "Honeymoon Canyon" near Batu Mamak and goes all eh through incredibly beautiful canyons. The stretch has 2 long rapids and some shorter ones, graded 3-4. The starting pint can only be reached by walking 30 minutes. This walk leads through the jungle and via a narrow suspension bridge over the river. An alternative is to raft only the first 7 km with 2 rapids, which takes 1.5 hours. The Lower Run offers time to see the abundence of birds and monkeys alongside the beautiful jungle. Between the end of the Hula-huli run and the entry to the Honeymoon Canyon is so-called "Nightmare", a drop of 3-4 meters with a water speed of 40-50 km/hr. It is graded 6.The "Shit Creek", grade 3, is where the small river Ais Kuais enters Sungai Asahan. There is small waterfall and a nice clear pool in this area.