Mas o Menos

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Quick Facts

  • Class: V-
  • Type: Composite: Ledges with Landslide Debris
  • Length: 250 meters (820 feet)
  • Alternate Names:
  • Previous Rapid: Postre
  • Next Rapid: Right Turn
  • Interactive Map: Futaleufu River Valley
  • River Section: Lower Futaleufu, Puente Futaleufu to El Macal


A detailed sketch illustrating the key kayak lines of Mas o Menos
A detailed sketch illustrating the key kayak lines of Mas o Menos

Mas-o-Menos is the second most intense rapid on the Lower Futaleufu second only to Casa de Piedra. The rapid is created by a long series of ledges constricted by landslide debris coming off the river-right side. The landslide effectively divides the rapid into an upper and lower section.

The upper section is characterized by random ledges and an almost ninety degree left turn in the river. At river-center there is a large rock known as Whale Rock and an associated hole known as the Whale Tail to river-right.

The lower section forms after the landslide on river-right compresses the channel into a spectacular v-wave, (called the Jaws of Mas o Menos) down the middle. After the Jaws there are a series of explosion holes followed by a huge breaking wave known as Compton’s Wave or Compton's for short. Compton’s was named due to the random scattering effect (Compton Effect) it has on kayakers leaving it.

Compton's Wave & the Compton Effect

Compton’s Wave acts like a diamond splitter, that scatters kayakers almost randomly to the left or right. To the LEFT lies a path that leads out of the rapid to the Promised Land. To the RIGHT is the Ledge Hole Staircase. What happens after colliding with Compton’s Wave will determine whether a kayaker will get MORE or LESS (Mas o Menos).

Like the Compton Effect, kayakers coming in get scattered all directions.
Like the Compton Effect, kayakers coming in get scattered all directions.

High and Low Water

At higher flows Whale Rock can turn into a dangerous mid-river pour-over. At very high water The Jaws of Maso o Menos can become a two story monster. Lower water exposes more rocks in the river bed, especially along the river-left sneak route, exposing paddlers to the risk of head and neck injury should they flip.


Scout from shore on river-right. Get out of your kayak above the fan shaped Landslide Delta (debris field) at the Scout Eddy.


Coming over the first ledge-hole across from the Landslide Delta on the river-left sneak route.
Coming over the first ledge-hole across from the Landslide Delta on the river-left sneak route.

In the upper section of Maso-o-Menos there is a large rock and associated wave called Whale Rock and Whale Tail respectively. Give this feature a wide berth on your left as you head for the Landslide Scouting Eddy. At high water, in the lower section, the Ledge Hole Staircase is the greatest hazard. The ledges on river-right create violent retentive hydraulics that should be avoided if you can. Just below Compton’s Wave, on river-left, is a small, steep, violent, pocket-hydraulic, called Compton’s Pit that will catch any initiate paddler unawares. After clearing Compton’s Pit you will need to dodge an offset wave-hole or two before coming to the Promised Land.

Play Opportunities

In the Upper Section there is a long surf-wave on river-right that often has a breaking face, it is called the Dolphin Wave. To access this wave use the eddy on river right below the ledge-hole or catch it on-the-fly. The super fast v-wave called The Jaws of Mas o Menos offers world-class, big-water surfing if you can keep you mind off the explosion waves and holes that lie behind it.

Where to Swim

Swimming in the main channel of Mas o Menos is not something you want to consider. There is little anyone can do to help a swimmer until the end of the rapid. You will be on your own out there. The waves and holes are huge which creates the extreme danger of a flush drowning scenario developing. If you do find yourself in the water try and swim toward river-left as it avoids the ledge holes on river-right.

Where to Rescue

Punching through the second ledge-hole with the Jaws of Mas o Menos in the background.
Punching through the second ledge-hole with the Jaws of Mas o Menos in the background.

For the sneak route rescue boaters can position themselves in the large eddies along the river-left bank staying one eddy ahead of the main group until all are safely down. To set-up rescue for the main channel position the safety boaters at the bottom of the rapid. Having one boater on the left side and another behind the Ledge Hole Staircase, on river-right, covers most of the bases.

Where to Portage

If you think you will need to portage this rapid reconsider your plans to run Mas o Menos, there is no good good way around it. The intuitive idea of getting around the Jaws of Mas o Menos, by putting in behind the Landslide Delta, exposes you directly to the hazardous Ledge Hole Staircase.

Running the Rapid

There are two options for running this rapid

Center Line:

Rafters punching the third ledge-hole with Compton's Wave visible on the right.
Rafters punching the third ledge-hole with Compton's Wave visible on the right.

Head over to river-right, to the eddy above the landslide. From there scout the rapid from shore on the Landslide Delta. After thoroughly scouting paddle upstream and ferry out to river-river center. Aim your kayak for the Jaws and the wave-holes behind it. After the Jaws look for the highest wave on the rapid - this is Compton’s Wave. Because the waves are so big in the center you will only be able to spot Compton’s when you are on top of one of the waves. Use the crest of Compton’s as your homing beacon. Aim for the apex with your boat pointed toward the left. Don’t power through the left shoulder as you will end up in Compton’s Pit. Compton’s Pit is a steep, violent hole that needs to be "barely" skirted by going right of it. Once you are past Compton’s Pit power hard to river-left and exit the rapid. The move around Compton’s Pit is a delicate one. If you give the hole too wide a berth you will end up going right, into the Ledge Hole Staircase. Successfully negotiating the Ledge Hole Staircase is a matter of skillful hole-dodging, dogged determination and luck. In Mas-o-Menos, if you go left you get LESS and if you go right you get MORE.

River-Left Route:

This line avoids the center of Mas o Menos and could rightfully be called a sneak route. After rounding the bend from the Puenta Futaleufu (Futaleufu Bridge) you will see a few small ledges on river-left. Stay to the right of these ledges and cut left to avoid the Whale Rock and Whale Tale. Here you will find a nice eddy to regroup before you start your eddy hopping down the left side. Your strategy will consist of paddling off the left shore just enough to get outside the rocks and then come back into the two large eddies that are available on this line. This is like paddling a much smaller river. Drive hard into the eddies just behind the rocks that creates them. Be careful as you are cutting across the micro-tongue at the top of the first eddy, there is a small (by futa standards) grabby hole just to the right of the micro-tongue. From this first eddy you can look downstream and see the second eddy and visualize how to get into it. After the second eddy you can peel-out and go with the flow to the bottom of the rapid.

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  • Copyrights: (Copyright © 2006, Expediciones Chile) All photos, maps, diagrams, text and computer code is the copyrighted property of Expediciones Chile with all rights reserved.

  • Terms of Use: Any type of reproduction, republication, or re-transmission for commercial use is prohibited without the expressed, written permission of Expediciones Chile. Users of this Wiki guidebook may print copies of the text, images and diagrams for personal river running use only. Users may not alter the diagrams or text without expressed written permission of Expediciones Chile. Users must read and acknowledge the disclaimer before printing. Printing implies acknowledgment of the disclaimer.


  • Disclaimer: Under no circumstances should paddlers substitute the information and diagrams in this guidebook for their own sound judgment on the river and their collective experience running rivers. This guidebook is based on Expediciones Chile's twenty years of experience running the Futaleufu River. However, the diagrams and descriptions found here are only approximations of what paddlers will find on the river once they get here. They are not to scale and nor are they completely accurate. Water levels change, rocks move around, landslide debris can enter the river at any time making the diagrams obsolete. Expediciones Chile also reserves the right to update these diagrams and descriptions at any time as we find better ways to illustrate and discuss the rapids. Use this guidebook at your own risk.

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