Built Worldwide

A radical design for quick access when thru hiking.

The Big Mountain features a quick access center zip with the additional capacity of a top loader. This pack has a long center zipper that splits the top of the shroud in half, allowing you to easily see and access all your gear. With a beefy light frame, two vertical long pockets and a removable lid. This pack has everything you need for an overnight trip or that dream trip up the big one.

  • Top Loading design for easy packing
  • Two vertical long pockets for external organization
  • Water bottle pockets keep hydration handy
  • Hydration reservoir compatible
  • Double Wrap waistbelt is removable for travel
  • Adjustable ice axe loops for trekking poles or ice tools
  • Volume: 3966 cu-in (65 L)
  • Weight: 5 lbs 4 oz (2.4kg)
  • Dimensions: 25”x12.2”x7.6” (64x31x18cm)
  • Frame System: Adventure Frame
  • Country Of Manufacture: Other
  • Intended Use: Extended Backpacking, Multi-Day Backpacking, Thru Hiking

Frequenty Asked Questions

We're moving to a kitted system so that we can design and build packs and frames that are optimized for integration based on the function of the product. There are some cool new things in the works. In the mean time, we may be able to accommodate pack only orders based on available inventory - contact MR Customer Service or call 406-585-1428

As much as we would like to be able to offer our military/LE/ firefighter customers a discount on our packs, we have government contracts in these markets that prevent us from doing so.

The only repair that we can offer on Dana Design products is a replacement back foam pad on packs with the ArcFlex body panel design. We can ship the foam to you and you can easily install it yourself without having to send the pack in to be repaired. Replacement back foam pads are $15.00 plus $5.00 for shipping. For any other Dana Design pack repairs, please contact Marmot or try the following reputable gear repair companies:

Marmot Warranty:

(888) 311-2900

Mon - Fri : 7:30am - 5pm (PST)


Boulder Mountain Repair:

2744 47th St.

Boulder, CO80301

(303) 499-3634


Rainy Pass Repair:

4415 Stone Way N.

Seattle, WA98103

(206) 523-8135


We are not set up to perform custom work on individual orders and no, we cannot build a pack for you in a custom color. If your concern is in regards to sizing please give us a call at 406-585-1428.

Also, please know that modifying your Mystery Ranch pack may void the lifetime warranty, so please think first before you start ripping straps off and cutting holes in your pack to make it more aerodynamic for winged flight.

First, start by washing your pack with hot water in the shower. Use a mild detergent like Dawn to get minor dirt and grime out of your pack. Dry the pack out of direct sunlight. DO NOT USE HARSH CHEMICALS TO CLEAN YOUR PACK. If you need to get odors/blood out of your hunting pack, please use Atsko Sport-Wash Laundry Detergent

We always recommend that you size down for the waist belt. If you fall in-between sizes on the yoke, we recommend that you size up.

Mystery Ranch accepts returns for a refund within 60 days of the original purchase date. Items must be returned in brand new, unused condition, and shipping charges are non-refundable. Please give us a call at 406-585-1428, and we can get you set up with a Return Authorization (RA#).

If you think that you qualify for a pro discount, please give us a call at 406-585-1428. Thanks!

If you are in need of a different size yoke or waist belt, please give us a call at 406-585-1428.

Why did you add a production facility in the Philippines?

We added a production facility at Clark Field in the Philippines because we needed the capacity to build for customers both domestic and abroad who don't require (Berry compliant) U.S. production and / or don't want to pay a premium for products built in the U.S.A

How do I know if the pack I want is made in the US or PI?

It will be noted on the product page on our website and you are always welcome to call us and ask if you don't see the "US" or "world" icons that denote production location.

Is the quality of the packs the same?

Yes. We still seek out the highest quality materials and construction methods available. We have rigorously run through every product and inspected them ourselves to certify the quality of a good matches our US standards. The quality is the same, so much that we have to mark the product so we don't confuse the two ourselves. Our distributors who have received product from the U.S. and from Clark Field have not been able to tell the difference without looking at the label.

How do you ensure the quality is the same?

Our sewers at Clark Field are trained using the same protocol we use in the United States. We spend the time to send our trainers and inspectors to the P.I. to consult and educate the sewers on our methods and quality standards. The short of it: PI production workers are trained by our people, they are our people.

Will Warranty or Repair procedures change?

No, our warranty and repair will remain the same regardless of production location. We hang our hat on being the most durable and comfortable packs on the market and that will not change.

For more information please contact MR Customer Service or call 406-585-1428

I received this pack right before a five day climb and traverse in the Cascades. I was apprehensive since I did not have time to test it out and really dial it in, but I need not have worried. The pack preformed well above expectations.

First, I watched the video on how to adjust the pack. It proved to be simple and easy if you have a person to help, but a bit tougher for just one person to adjust alone.

On the trip, the pack handled 50 pounds amazingly well. The suspension transferred the weight perfectly. The belt was easy to adjust and stayed adjusted, and the pack never sagged or drooped due to the weight.

The pack is also very well built and durable. The terrain was steep, rocky, and often very brush, but the backpack came out unscathed. The zippers are impressive and appears to be built to last, and the zipper configuration made access to all parts of the pack very simple and easy.

The top "brain" pockets are well thought out. I liked having two separate pockets and the large, fold-open design was very convenient.

I have since carried it on three other backpacking and climbing trips, and have not had a single thing to complain about. I have recommended this pack to my hiking partners, and I'm sure they are getting tired of hearing me rave about how well it carries.
I bought this pack when it first came out. I have a solid history with Mysteryranch packs because of neck and back injuries they are the only packs that I really find comfortable, Until now. I have owned this pack for roughly a year and have used it twice not to mentions all of the trips up and down the stairs trying to get it to fit right.. Pros, I like the overall design easy access to pack, top pocket large enough to flop a three liter MRS bag into for hydration and I like the fabric. I am not overly fond of the smaller straps and buckles for me with gloves on they are impossible to operate and I only back pack in the winter. Never the less they do there job adequately. My real complaint comes with the lumber pad which is nonexistent and after three weeks of trying to get it to fit right I called Mysteryranch and ask does this thing fit differently then your previous pack and yes it does. The waste belt should sit above your hips not cradling them like the previous packs at least that is what I was told. To be blunt I find it almost useless when wearing it as I was told to. It pushes your pants down and is constantly slipping down. Now maybe this design will work for others but not for me I have even tried wearing it with the belt cradling my hips but without the larger lumber pad useless, and as I have had it for at least a year it will probably end up on eBay. Could be a great pack with the older style waste belt and lumbar support . I applaud the idea of trying to reduce the weight and the basic concept however there is an old saying. If it ant broke don't fix it and I would add improve on it. Fortunately I own a G5000 with the Cush lumber wrap so I will still be out backpacking this winter and this bag will end up on eBay or the boy scouts..
I've been carrying MR packs for about 5 years, since before I left the military. Now that I'm out, I wanted something that was comfortable, durable, and spacious. I found the pack I was looking for in the Big Mountain. It is one of the most comfortable packs that I've ever worn. I routinely hike over 50lbs, and occasionally over 70 if I'm doing a Mountain trip. I have a couple of very VERY minor gripes. So farI don't really like is the lack of a bottom opening for my sleeping bag. While I enjoy the center zip for most times, when I really need to cram things in, it would be useful to have another access point.