Seek Outside Gila 3500 Backpack Review

Seek Outside Gila 3500 Backpack Review

The Seek Outside Gila 3500 (57L) is a 2 pound 15-ounce external frame backpack capable of carrying heavy loads, up to 100 pounds. It’s made with a waterproof laminate fabric called XPac which is more durable than Dyneema Composite Fabric (formerly called cuben fiber) and less expensive. While the weight carrying capacity of the Gila is overkill for ultralight thru-hiking, the comfort provided by the pack for heavier 25-45 pound loads is quite impressive. External frames are well ventilated, so sweating isn’t an issue. The wide hip belt provides an excellent wrap around your hip bones and doesn’t slip, while the stiff frame keeps the pack weight off your shoulders. Let’s take a closer look at what makes this pack tick.

Seek Outside Gila 3500 Backpack



The Seek Outside Gila 3500 (57L) is an adjustable-length, external frame backpack that's ideally sized for lightweight backpackers who want a ultralight-style pack that weighs less than 3 pounds to carry loads in the 30-50 pound range. This is a weight range that's beyond what many other ultralight-style and cottage lightweight backpacks can carry today, but well within the Gila's wheelhouse.

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Specs at a glance:

  • 42-47 ounces
  • Frame: external, adjustable torso length
  • Fabric: X21 XPac; other grades of XPac are also available
  • Suspension is 500D Cordura and 3D spacer mesh. Hypalon and 500D Cordura reinforcements
  • Sizing:
    • 14″ – 20″ torsos without extensions , 18″ – 21″ with 2 inch extensions.
    • One size harness micro adjustable to any torso length within fit range
    • Interchangeable hipbelts in three sizes, to fit waists from 29″ to 42″
  • Max weight limit: 100 pounds
  • MSRP $339

Internal Organization and Storage

The Gila 3500 is laid out like an ultralight style backpack with a roll-top closure, a long rear mesh pocket, and side water bottle pockets. The rear pocket is made with heavy-duty mesh to prevent ripping while the side pockets are hard-faced with 500d Cordura for extra durability. There are two webbing loops inside the pack bag to hang a reservoir with a single hydration port behind the shoulder harness.

The Gila 3500 has a long mesh back pocket that can store a ton of gear
The Gila 3500 has a long mesh back pocket that can store a ton of gear

The side water bottle pockets can hold two 1 liter water bottles, which are reachable while you’re wearing the backpack. The pockets have a fabric slit in the bottom to drain water, but you need to be careful not to put small items there, lest they slip out. There’s also an elastic cord with a cord lock that runs through the top of each side pocket, so you can cinch it tight and keep taller items like tent poles, a paddle, or fishing rod secure. The lower side compression strap runs above the side pocket so there’s no need to ever routed it through or over the pockets like other backpacks.

The Gila doesn’t have hip belts pockets, although they are available as an optional add-on. The outside of the hip belt has a pair of webbing straps to attach them to. Both of the shoulder straps have external daisy chains that are convenient for hanging a GPS or camera pocket.

Gatekeeper compression strap buckles
Gatekeeper compression strap buckles

External Attachment and Compression System

The Gila has three tiers of side compression straps that give you a lot of flexibility to lash gear to the side of the pack or compress your load. The webbing straps are not long enough to loop behind the backpack, although the hardware doesn’t prevent you from running your own webbing straps there (for example, to attach snowshoes to the back of the pack). The side webbing straps are attached using plastic gatekeeper clips, which are like bachelor buckles but with wire gates to prevent the webbing from slipping when the strap is not tensioned. You can open the gates while wearing gloves by simply squeezing the buckle, which will pop the gate open.

The roll top closure buckles closed on top of the packbag and is held in place by a Y strap.
The roll-top closure buckles closed on top of the packbag and is held in place by a Y strap.

The Gila also has a pair of sleeping bag straps at the base of the packbag that can be used to attach gear, like a tent or sleeping bag, to the bottom of the pack. You can use these to hold a bear canister or strap it under the Y strap on top of the pack.

Backpack Frame and Suspension

The Gila 3500 uses the same adjustable length, external frame suspension system as all of Seek Outsides’ other backpacks. The frame and suspension system is nothing short of ingenious, providing a level of modularity and many types of adjustments that are not available on conventional internal frame backpacks.

Adjustable torso length

First off, the torso length of the Gila 3500 is adjustable by raising and lowering the height of the shoulder harness. If you have a very long torso, you can add vertical extensions to the external frame to make the torso length longer.

The shoulder pads can be moved up or down to adjust the pack's torso length
The shoulder pads can be moved up or down to adjust the pack’s torso length

Adjustable load lifter angles

The angle of the load lifter straps is also adjustable so you can maintain them at a 45 degree angle. To change the angle, you raise or lower a buckle the runs along the front of the shoulder strap. Many high-volume expedition packs have this feature and it’s quite useful to counter loads that pull you backward and off-balance.

External frame

The external frame is made using aluminum tubing and slightly curved to conform to the curvature of your back. Being an external frame, back ventilation is good because there’s an air gap between your shirt and the pack bag.

The frame is extremely rigid and there is no sag of the pack bag against your back. If you want, you can lengthen the torso so that the entire load rests on your hips, very unlike an internal frame pack where the weight is always split between your hips and shoulders by design.

The pack bag is secured to the frame with webbing loops, locking nuts, and pole sleeves that keep it properly positioned. If you want, you can replace the pack bag provided with the Gila with a higher volume version sold by Seek Outside or attach additional accessories. Yes, this one frame works with many packs.

The frame has a noticeable curve which helps direct the load into the hip belt and keep it off your back for better ventilation.
The frame has a noticeable curve that helps direct the load onto the hip belt and keep it off your back for better ventilation.

Horizontal stay

There is a horizontal stay positioned behind you back that keeps the pack bag from barreling or bulging into you back if you overstuff the pack bag. It’s quite effective. This can be an issue on any roll-top backpack if you try to overstuff or over compress it.

Comparable External Frame Backpacking Packs

Make / ModelVolume (L)WeightPrice
Kelty Trekker 6565L5 lbs 2 oz$180
Kelty Yukon48L5 lbs 1 oz$170
Kelty Tigoa90L5 lbs 9 oz$200
ALPS Mountaineering Zion64L4 lbs 15 oz$170
Mystery Ranch Terraframe50L, 80L5 lbs$400
Seek Outside Gila57L2 lbs 10 oz$339
Seek Outside Divide74L2 lbs 12 oz$349
Seek Outside
Unaweep 4800
79L2 lbs 11 oz$399
Vargo ExoTi AR246L2 lbs 12 oz$300
Vargo ExoTi 50L2 lbs 11 oz$300
ZPacks Arc Blast55L1 lb 4 oz$349
ZPacks Haul62L1 lb 8 oz$325

Hip Belt

The padded hip belt is quite wide (5″) and provides an outstanding fit that won’t slide down your hips even if you wear it fairly loosely. It’s attached to the bottom of the frame and floats freely, conforming to your anatomy, rather than making you conform to its shape like many internal frame backpacks.

Seek outside changed their hip belt about six months ago (on all of their packs), shifting from a single strap and single buckle to two buckles, attached to two straps running along the hip belt. This was to remove a single point of failure, while improving the wearer’s ability to tighten or loosen the top and bottom edges independently. While the new hip belt does improve the fit, it adds two long straps to the hip belt which can get in the way of each other when you attach and adjust the hip belt. Seek Outside has a good video on their website which shows how to manage these straps with tri-glides, which helps reduce their nuisance factor.

Closeup of the improved Seek Outside hip belt
Closeup of the improved Seek Outside hip belt


The Seek Outside Gila 3500 (57L) is an adjustable-length, external frame backpack that’s ideally sized for lightweight backpackers who want an ultralight-style pack that weighs less than 3 pounds to carry loads in the 30-50 pound range. This is a weight range that’s beyond what many other ultralight-style and cottage lightweight backpacks can carry today, but well within the Gila’s wheelhouse.

There are lots of good reasons why people have to carry this much weight on a backpacking trip.

  • Wilderness backpackers that don’t have easy access to towns for resupply have to carry more gear, food, and fuel
  • Winter backpackers have to carry more sleep insulation, food, fuel, and technical gear
  • Guides, trail maintainers and other wilderness professionals have to carry extra communication, medical, and search and rescue gear
  • Dads get stuck carrying their own gear plus their kid’s gear and food on backpacking and camping trips.

If this describes you, I’d recommend checking out the Gila 3500  and its adjustable length external frame suspension system. Carrying one of Seek Outside’s external frame backpacks is nothing like that old Kelty or Wenzel pack you carried as a kid. Based on the Seek Outside external frame, the Gila 3500 is well-sized and appointed for lightweight backpackers who have to carry more weight than they might like but appreciate the layout of an ultralight-style, roll-top backpack pack.

Disclosure: Seek Outside loaned the author a backpack for this review.

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  1. I realize they are quite different. Still, I would love to hear which one feels more comfortable to you when carrying around 30 lbs if you can still remember it. This is near the the upper recommended weight for the Mariposa and I wonder if it is still comfortable at that weight when compared to the Gila. I hate heavy carries with an uncomfortable pack and I would gladly take a weight penalty of a pound if the pack feels much more comfortable on my back after a resupply or when having to carry lots of water. Also, being able to use a pack for more than one thru-hike without trashing it would be really nice.

  2. ok. When you get up to 30-35 pounds, the Mariposa starts to max out. I ounce tried to carry 40-45 pounds with it and it almost killed me (figuratively speaking). The Gila handles that with ease, in part because it has such a wide hip belt and the frame won’t collapse because it’s metal. The Xpac will also be much more durable than the robic nylon on the Mariposa. You’d have to try really really hard to trash the Gila on a thru-hike. No so much with a Mariposa. I’ve shredded one of them in a day.

  3. Is the Divide just a larger version of the Gila? If so, it seems like the better way to go given it is larger and only 2 oz heavier but I may be missing something. Thoughts?

  4. Are you planning to review the recently released Seek Outside Flight pack? I am really torn between getting the Flight pack and the Gila. Unfortunately, there aren’t any Flight pack reviews out yet.

  5. Thanks for the review.

    Trying to decide between this and the Divide to replace my Mariposa. I don’t really *need* the extra capacity of the Divide but given the minimal weight and price difference, I’m leaning toward the Divide.

    Do you know if the 57L of the Gila is total or is that the main bag and the side and front pockets would be additional?

    • Don’t know offhand. Call them.

      • For those who might be interested, the 57L of the Gila does not include the pockets. Found the info below on their site. Must have missed it the first time I looked

        Volume – 3500 ci | 57 L (not counting pocket volume)
        Face Pocket adds roughly 800 ci.
        Two side water bottle pockets sized to hold two Nalgenes each.

  6. Hi Philip,
    Would you feel confident hiking off-trail with the mesh on the rear pocket on this pack?

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