Long Term Review: Osprey Mutant 38 Pack

Osprey has the reputation for making extremely comfortable packs and the redesigned Mutant 38 doesn’t disappoint.  This spacious 38L top loader fits like a glove, making it easy to forget how much heavy gear’s in it.  It’s also a very well thought out and versatile pack with features for just about any alpine mission.  While it’s not perfect, the Mutant’s a fantastic tool for the mountains.

Note: Osprey updated this pack for 2018. Click here for the review on the new version.


  • Size: 38L (I tested the M/L size but the pack also comes in an S/M, 35L version)
  • Design: Top loader with a removable lid
  • Weight: 1200g
  • Material: 210 denier nylon


  • Removable lid with helmet bra
  • Two pockets on the lid (if you count the helmet bra pocket)
  • Third pocket just inside the pack
  • Hydration system compatible
  • Integrated FlapJacket with pocket
  • A-Frame ski carry loops
  • Dual ice tool carry
  • Side compression straps
  • Waist belt has gear loops and is designed to be reversed and clipped behind the pack.
Osprey Mutant
A cold snap in Squamish, BC froze the iconic Chief allowing me to climb a variation of the summer rock route “Ultimate Everything” on tools.

The Mutant 38 is an incredibly versatile pack.  It carries a ton of gear when it has to but can also be stripped down to a sleek, low-profile package for climbing.  To strip the pack down the top lid is removed, which also takes the helmet bra with it.  The side compression straps can then be removed (I prefer to use them to actually compress the pack though) and the framesheet pulled out.  To complete the transition the waist belt is flipped around backwards and clipped through the ice pick loop.  The result is a short and sleek package that doesn’t get in the way of the harness, allows the climber to look up without the helmet hitting the top of the pack and is a bit lighter.

Osprey Mutant
On the right is the stripped down pack with the waist strap flipped around backwards. The removed components on the left (the lid and frame). With the Flap Jacket down the pack is quite sleek and doesn’t get caught up on rock horns or brush much.

One of the unique features of this, and the Variant, line of Osprey packs is the “Flap Jacket”.  It’s basically a flap of fabric that’s used as a back-up lid when the main lid is removed.  A great feature in general but one that I think could use a touch more finesse in the design.  When the lid is removed this flap works wonders.  It streamlines the top of the pack so it doesn’t catch on anything and ensures that no snow, rain or other debris get inside.  When it’s not in use, however, it can be a bit annoying as it doesn’t have a pocket or velcro strap to get it out of the way.  I found if I wasn’t careful I could sometimes mistakenly clip the flap down and not the main lid, not a big deal just a bit annoying.

Osprey Mutant
View of the loaded Mutant from the back. The Flap Jacket clip can be seen next to the handle of the right hand tool.

The pack features some A-frame ski carry straps which would make it a reasonable option for ski mountaineering.  However, it doesn’t have a separate snow safety equipment pocket a dedicated ski pack.

Osprey Mutant
The side view of the Mutant 38. The removable side compression straps can be tightened at the top, middle and bottom. The waist strap also features some ice clipper slots and a gear loop that can be tucked away. The grey side strap on the bottom is for an A-frame ski carry.

The ice tool carry system is set-up well to attach to any type of axe you think of from summer mountaineering axes to technical winter tools.  It’s also easy to use when wearing gloves.

Osprey Mutant
The bottom part of the ice tool carry system. I found that I was actually able to remove my summer alpine tools (Sum’tecs) with the pack on if I wanted to.

I really like that the pack has a helmet carry system.  It’s just too easy to accidentally destroy a helmet stuffing it in the top of a climbing pack!  However, when my helmet is strapped onto the Mutant there’s still a lot of play.  As a result the helmet would flop around a bit when walking.  Now this hasn’t been a functional issue most of the time but my helmet did end up falling off the pack once during a serious bush whacking episode.  Still better than putting it on the inside of the pack though!

Osprey Mutant
The pocket on the inside of the Flap Jacket is just big enough to keep the smaller items like snacks and a headlamp and so on from rattling around in the bottom of the pack. The color staining is due to a leaky water bottle not anything to do with the pack itself.
Osprey Mutant
The helmet carry system. The strap by the back of the helmet is a little loose and allows the helmet to flop around a bit.

After using the pack a bunch this fall and winter I’ve found it to be both versatile and functional.  It carries a heavy load extremely well, is big enough to pack what you need into the base of a climb but still compresses down to a sleek climbing pack when things get vertical.  And while there’s some room for improvement it’s become my go-to alpine and ice climbing pack.

Pros: Versatile, functional and comfortable

Cons: Floppy helmet carry, no pocket for the Flap Jacket

Overall: This is an amazingly versatile and comfortable pack that excels at alpine and ice climbing.

A review sample was provided to us by Osprey but of course this did not influence us in any way.