A good 40 liter mountain pack is easy to find these days, such as the Black Diamond Speed 40 and the Patagonia Ascensionist. However, as the name suggests Osprey’s new Mutant line of packs promise to evolve and adapt to different situations. Osprey makes a 22 liter, 38 liter, and a 52 liter version of the Mutant. We picked up the 38 liter version to see if Osprey can make a pack that can adapt to different roles.  


The Good

As Osprey promised, the Mutant 38 is a great bag for many different activities. To make it suitable for climbers, the pack has ice tool holders, a rope attachment strap, gear loops, ice clipper attachment points on the hip belt, and a removable helmet net. It has pockets on the side to hold snow pickets for glacier or alpine travel. Although the Black Diamond Speed 40 and the Patagonia Ascensionist also have side compression straps, the Mutant’s has dedicated reinforced ski carry straps to carry skis in an a-frame configuration. For hikers it has an internal hydration pouch with external openings for a hydration tube. Other bags have some of those features, but as of now no other 40 liter bag can boast all of those features.

The Mutant 38 making the most of the outside storage.

The next impressive aspect of this pack is it’s scalability. When scaled up it holds 38 liters in the main compartment and lid. Storing some gear on the outside of the pack such as the helmet, ice tools and rope help the user get the most of the 38 liter capacity. The shoulder straps and waist straps are padded enough to comfortably carry around 40 pounds, while being small enough to not hinder climbing mobility. When scaled down, the Mutant 38 can easily be used as a small climbing pack or a day pack without seeming too big or heavy. 

The Mutant 38 scaled down on a multi-pitch climb.

The Black Diamond Speed 40 can have its lid removed but that leaves a small drawstring opening exposed upwards that can allow dirt, snow and water to get in. The Mutant 38 fixes this problem with the internal flapjacket, which folds out and clips to the straps that the lid would if it was still attacked. This keeps gear clean and dry even with the lid removed.

With the lid removed, the flapjacket buckles over the top opening.

Besides all the extra features and its wide range of size and weight capacity, it is still a great bag. The shoulder straps never rolled or were uncomfortable, which is generally what happens when overloading a pack. The hip belt tightens by pulling the straps from the hips towards the center of the body, which makes adjusting the tightness of the hip strap easier and more comfortable to do while wearing the pack. The frame is rigid and light plastic, and the compression straps do a great job of pulling the weight close to your body.

Holding the weight close to the body.

The Bad 

As versatile as this bag is, there is a feature that would make this bag just a bit more versatile.  There is no internal compartment so if the lid is removed there is no place to put a small items such as keys or a wallet. Most smaller climbing bags have a smaller pocket somewhere so you don’t have to keep your car keys loose at the bottom of your bag. The Patagonia Ascensionist does not have a removable lid, bit it does have a zipper pocket on it’s lid for smaller items.  

Loading the bag

There are also some elements that take away from the scalability of the bag. Although the hip belt is big enough to carry heavy loads, there is no way to scale it down (as you can on the Ascensionist) or remove it completely. It is sewed in place and you are stuck with it the way it comes. 

The hipbelt

Also, if the lid is removed and the flapjacket is used, there comes a point where you scale the bag down too much and the flapjacket interferes with the rope strap. The stap cannot be used and needs to be constantly stuffed into the main compartment. A simple fix would have been moving the attachment point for the strap lower on the front of the bag or making that strap removable.

When the flapjacket is cinched down, the rope strap has no where to go.

The Verdict

If you’re looking for only one bag that can be used for climbing, hiking, and skiing that can scale between 20 and 40 liters than this is a great option. It is big enough to carry everything you need for a long ice climbing approach, but can also be scaled down small enough to carry your walk off shoes, water and some snacks on a long multi-pitch climb. Small adjustments would make this bag just a bit better, but overall the Mutant 38 would be a great recommendation for the mountaineer that experiences all four seasons.

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