Also known as: Sungai Alas
Gunung Leuser rainforest gorge, virgin jungle, riverbank camping with BBQ, hot springs near Ketambe

Whether there is a river here on your dates, and what kind of water it is.
Rain-fed monsoon-influenced; Alas is the longest river in Aceh, draining Gunung Leuser to the Indian Ocean
Effectively year-round, rain-fed with heavy jungle rainfall (est)
Drier months preferred; Leuser rainfall high year-round (est) (Confirm.)
Warm tropical water (est)
Flash floods possible after heavy Leuser rain; sudden jungle downpours
A river changes grade with its level. These grades describe a normal flow - in flood the same run is harder, and often a different run entirely. Check the gauge before you commit.
Grade 2-4 (predominantly 2-3); sources conflict (Confirm.)
Whitewater rafting (also inflatable kayak)
Short 1-day Ketambe-Kutacane vs multiday extensions continuing downstream past Kutacane
Casual visitors handle the day run; multiday for adventurous groups; calmer sections family-capable (est)
Gorge rapids below Ketambe; principal challenge is wilderness remoteness and logistics rather than technical whitewater (est)
Remote gorge; strainers/log jams, wildlife encounters, very limited rescue access (est)
Ketambe to Kutacane (Gunung Leuser gorge)
Low; remote wilderness with little traffic
Gunung Leuser National Park area; permit and guide arranged via operator (Confirm.)
Permits and operators change - confirm before booking.
Road Kutacane-Ketambe (~35-45 km) to put-in; take-out near Kutacane (Confirm.)
Operator vehicle from Kutacane or Ketambe lodges
Riverbank tent camps on multiday trips (BBQ, campfire); simple lodges in Ketambe
Equipment provided by operator; expect no mobile signal within the gorge (est)
Ketambe Adventure, Arika Tour and Travel, Adventure Indonesia, Ketambe village guides; hub Kutacane/Ketambe
Remote wilderness, wildlife, flash-flood risk; requires self-sufficiency and experienced outfitter
Very limited; road access only near start and end points
Guided expedition required; local Ketambe river crew
This profile is desk research, compiled from public sources - not a first-hand river run report. Coordinates are approximate.