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Gossamer Gear Mariposa Plus Backpack REVIEW

Removable carbon fiber stays make it one of the lightest and most versatile internal frame backpacks on the market.


Overall Rating: Recommended

The Gossamer Gear Mariposa Plus is a highly refined and highly versatile backpack. If an ultralight backpacker wanted to purchase just one backpack, this would be it. With the stays in, this 20 ounce wonder will carry a 20 to 30 pound load with remarkable comfort, and its feature set is focused on what an ultralight backpacker wants and needs.

The primary reason the pack is not rated "Highly Recommended" is that the pack’s straight carbon fiber stays are not bendable to allow an anatomical fit to the user’s back. Switching to curved flat stays would create a more comfortable fit, and including shapeable stays would allow the user to create a custom fit. Also, I would like to see Gossamer Gear offer optional lightweight hipbelt and sternum strap pockets to further refine the pack for on-trail convenience. Finally, I feel that the pockets in the shoulder straps and hipbelt to insert socks for padding are getting a bit outdated; the provided foam pads weigh just 0.9 ounce total and can easily be sewn in to eliminate the Velcro closures.

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by Will Rietveld |

Gossamer Gear Mariposa Plus Backpack REVIEW - 1
The Mariposa Plus on a 6-day backpack in the Wind River Range, Wyoming.


Backpacking Light reviewed the original Gossamer Gear Mariposa backack in 2004. We were delighted with its light weight and load-carrying capacity, but noted that it needed a few refinements. The Mariposa has since been tweaked to near perfection. The new Mariposa Plus is essentially identical except it has a removable wraparound hipbelt and uses more durable fabrics. Therefore, my review of the Mariposa Plus, contained herein, pertains to both packs.

What’s Good

  • Removable stays, sternum strap, and hipbelt
  • Highly versatile; can be used as either a frameless or internal frame backpack
  • Very high volume to weight ratio
  • Very high carry load to pack weight ratio
  • Durable fabrics
  • Large capacity front and side mesh pockets
  • Comfortably carries 20 to 30 pound loads

What’s Not So Good

  • No hipbelt pockets
  • Stays cannot be shaped for a custom fit



2007 Gossamer Gear Mariposa Plus


Internal frame or frameless, top loading, drawcord closure with top compression strap


4200 ci (69 L) total; main body 2900 ci, pockets 500 ci, extension collar 800 ci (48 + 8 + 13 L)


1 lb 4.5 oz (581 g) measured weight with stays and supplied padding; pack with hipbelt 18.7 oz (530 g), stays 0.9 oz (26 g), shoulder strap padding 0.6 oz (17 g), hipbelt padding 0.3 oz (9 g); manufacturer’s specification 1 lb 4.1 oz (570 g) with stays

  Sizes Available

S, M, L (size L tested)

  Torso Fit Range

S fits 12-16 in (30-40 cm), M fits 16-20 in (40-51 cm), L fits (20-24 in (51-61 cm)


Body is 70d 2.2 oz/yd2 (75 g/m2) polyurethane-coated ripstop nylon, stress and abrasion areas are reinforced with 200d 4 oz/yd2 (118 g/m2) polyurethane coated ripstop nylon, backpanel is 30d 1.3 oz/yd2 (44 g/m2) silnylon


Durable fabrics, wide shoulder straps, removable padding in shoulder straps and hipbelt, removable hipbelt, removable carbon fiber stays, 11 inch extension collar, drawcord closure, Y-strap top compression, backpanel sleeping pad sleeve, one large front and three large side mesh pockets, front or side bungee attachment/compression system, interior hydration sleeve with two hose ports, one ice axe loop, removable sternum strap with whistle, three hipbelt lengths available, haul loop

  Volume To Weight Ratio

204.9 ci/oz with stays (based on 4200 ci and measured weight of 20.5 oz), 214.4 without stays (based on 4200 ci and measured weight of 19.6 oz)

  Comfortable Load Carrying Capacity

30 lb estimated comfortable load for an average person carrying the pack (with stays) all day

  Carry Load to Pack Weight Ratio

23.4 with stays (based on 30 lb and a measured weight of 1.28 lb)


$150 US




The main differences between the standard Mariposa and the Mariposa Plus are the more durable fabric and removable hipbelt of the Plus version; the pack volume and other features are the same. The Plus is made of 2.2 oz/yd2 polyurethane-coated ripstop nylon, compared to the standard Mariposa’s 1.3 oz/yd2 silnylon. The heavier fabric and removable hipbelt add about 3 ounces, which is a small weight penalty for the durability and utility gained. However, I have used the standard Mariposa, and find its silnylon body adequately durable for my needs, so the choice ultimately depends on the intended use.

The Mariposa (and Mariposa Plus) have received some useful refinements since the original version, with minimal weight gain:

  • Taller mesh pockets
  • Drawcord closure
  • Three pack sizes available
  • Removable hipbelt available in three sizes (Mariposa Plus only)
  • Internal map pocket
  • Lower and more adjustable sternum strap
  • More durable stay sleeves
  • Hydration sleeve with two hose ports

The following photo gallery will help familiarize you with the pack:

Gossamer Gear Mariposa Plus Backpack REVIEW - 2
Views of the Gossamer Gear Mariposa Plus. The frontpanel (top left) has a large bellowed mesh pocket plus loops to add a bungee attachment/compression system. The backpanel (top right) has a sleeve to allow the use of a sleeping pad for padding and weight transfer (the sternum strap pocket and camera case are my additions). The right side (bottom left) has two mesh pockets, and the left side (bottom right has one tall mesh pocket.

Frame and Suspension

The frame is the lightest to be found anywhere - two carbon fiber rods weighing 0.9 ounce. They have rounded aluminum caps to prevent them from puncturing the fabric. Although they are very light, they are straight and are not bendable to fit the curvature of the user’s back. More on this in the Field Testing section.

Gossamer Gear Mariposa Plus Backpack REVIEW - 3
The Mariposa Plus’s frame consists of two straight carbon fiber rods that slip into durable sleeves inside the pack. The two stays weigh just 0.9 ounce.

I really love the pack’s wide shoulder straps and hipbelt. They’re 3.5 inches wide and have openings (with Velcro closures) to insert either articles of clothing (e.g. socks) or the provided 3-inch wide, ½-inch thick closed-cell pads. Since the shoulder strap pads weigh just 0.6-ounce and the hipbelt pads weigh 0.3 ounce (that’s a total of 0.9 ounce for all four pads), it might make sense to simply sew in the pads and eliminate the weight of the Velcro closures.

The pack does not have load lifter straps or hipbelt stabilizer straps.

Gossamer Gear Mariposa Plus Backpack REVIEW - 4
The suspension consists of 3.5-inch wide shoulder straps (top left) with 3D wicking mesh on the underside, a sleeping pad inserted into a pad sleeve (top right) to serve as a padded backpanel and pack stiffener, and a 3.5-inch wide removable hipbelt (bottom) with 3D spacer mesh on the underside.

Features and Utility

The Mariposa Plus (and Mariposa) has an essential set of features to meet the needs of a lightweight or ultralight backpacker. For starters, several components (hipbelt, stays, padding, and sternum strap) are removable, so the pack can be stripped down to a frameless backpack weighing about 14 ounces. Like many ultralight backpacks, the outside of the pack is covered with three large mesh pockets (500 cubic inches total) capable of holding a lot of gear and keeping it readily accessible on the trail. The lower right mesh pocket is designed to make a water bottle reachable without taking the pack off.

Conspicuously missing are hipbelt pockets, and I highly recommend that Gossamer Gear design some optional lightweight pockets, perhaps in different sizes, that can easily be slipped on the hipbelt. Further, an optional sternum strap pocket would also be a desirable option for convenience on the trail. To accommodate it, the sternum strap would need to connect at one side rather than in the middle.

Although the Gossamer Gear website states that this pack has an inside "small map/permit/sundries pocket", my sample pack did not have it. Such a pocket would be a nice addition, and worth the miniscule weight. A length of elastic cord and cordlocks are provided (0.4 ounce) to create a bungee attachment/compression system either on the front of the pack or the two sides, using loops sewn into the seams.

The pack body is not large enough to hold a bear canister, but the Y-strap on top is designed to hold a canister carried on top of the pack. I don’t have a bear canister, so I was not able to test that feature. In normal use without a bear canister, the Y-strap is a little cumbersome to use compared to a single strap because of its extra length and tendency to get twists in it.

Gossamer Gear Mariposa Plus Backpack REVIEW - 5
The Mariposa Plus has an internal hydration sleeve and two hose ports (left). Also note the sleeves that hold the carbon fiber stays. The pack’s roll-down closure is secured with a Y-strap (right), which is designed to hold down a bear canister carried on top of the pack.

Although an internal hydration sleeve (and two hose ports) is provided, I find it more convenient to carry a smaller water bladder in the upper right side pocket (as shown in the photo gallery above). The side pocket location makes it much more accessible for refilling, and I offset the weight by packing a little more weight on the left side inside the pack.

Field Testing

I carried the Mariposa Plus on three backpacking trips and simply loved it. On two trips I carried all the shared gear and food so my wife could carry a lighter pack - this allowed me to test the Mariposa Plus with a heavier load. I carried 20 pounds on an overnight trip and noted that the Mariposa Plus carried the load much more comfortably than a frameless pack. On a 6 day trip in the Wind River Range in Wyoming my measured starting weight was 29 pounds. I marveled at how comfortably the pack carried the weight, in large part due to the pack’s wide, firm shoulder straps and effective weight transfer. The third trip involved carrying my overnight gear plus supplies to a remote aid station we manned for the Hardrock 100 Endurance Race in Silverton, Colorado. When packed with about 35 pounds of dense weight, I felt that the Mariposa Plus had exceeded its comfortable limit, but it did in fact carry the weight without damage to the pack or unusual discomfort to me.

Although the carbon fiber stays (along with a stiff sleeping pad) definitely help to support a heavier load, the stays are as straight as an arrow (in fact, they are arrow shafts!). There is no way to bend the stays to fit the curvature of your back. Consequently, the top of the pack tends to lean back (see first photo). The pack does not have load lifter straps to pull the top of the pack against the shoulders, because they would be ineffective with the unbendable stays. Switching to a curved flat carbon or fiberglass stays would be a lightweight option to attain an anatomical fit. Thin aluminum stays would be ideal because they could readily be bent to customize the curvature against the wearer's back, but they would increase the weight of the pack by about 3 ounces.

I tested the Mariposa Plus with several different sleeping pads I have, and found it to be amenable with the Bozeman Mountain Works TorsoLite, Gossamer Gear NightLight, Therm-a-Rest RidgeRest ¾, and Therm-a-Rest Prolite 3 Short. The NightLight is ideal because it provides a stiffer backpanel (for better weight transfer to the hips) with minimum thickness. The folded RidgeRest provides a lot of stiffness, but it’s 2.5 inch thickness pushed the pack’s center of gravity away from my back, which is undesirable for heavier loads. Inflatable pads provide a comfortably padded backpanel, but do nothing to stiffen the pack for weight transfer.

Gossamer Gear Mariposa Plus Backpack REVIEW - 6
A trick I used on a standard Mariposa pack to overcome the straight stay issue is to fold my TorsoLite pad so that it's square and stuff it into the bottom part of the pad sleeve. My wife sewed a strip of Velcro on the top edge to secure it. This modification pushes the bottom of the pack out and levers the top of the pack in closer to my shoulders, making the pack fit better.

Since the weight of the carbon fiber stays and foam inserts for the shoulder straps and hipbelt are so miniscule, adding up to 1.8 ounces, I made no effort to remove them from the pack to save weight. For me, the additional comfort and weight-carrying capacity are well worth the weight. I suspect other hikers will do the same, unless they intentionally strip the pack down and use it as a frameless backpack for loads less that about 15-18 pounds.

Gossamer Gear Mariposa Plus Backpack REVIEW - 7
The only problem I had with the Mariposa Plus was a seam came apart that attaches the elastic binding to the top of a side mesh pocket. My wife re-sewed it and there were no further problems.

On their website, Gossamer Gear notes that the mesh used for the sleeping pad sleeve has been reported to stain clothing, and they recommend giving it a good rinsing before using the pack. Also, they note that stitching on the mesh pockets may unravel (as mine did), and offer to repair existing packs at no charge. Both problems will be remedied in future production runs.


Because of its removable stays and other components, the Gossamer Gear Mariposa Plus (and Mariposa) is easily the most versatile ultralight backpack around. When stripped down, it’s a very comfortable and capable frameless pack. With the stays in, the comfortable range is extended to about 30 pounds.

When you hold the empty pack in your hand, it is hard to believe that it will comfortably carry up to 30 pounds, but it does. If your total pack weight is normally in the 20 to 30 pound range, consider getting the 20 ounce Gossamer Gear Mariposa or Mariposa Plus instead of a conventional internal frame backpack that can weigh 3 pounds or more. The standard Mariposa and Mariposa Plus are fully capable of carrying 20 to 30 pound loads with a good level of comfort. However, many conventional internal frame packs have additional features that fit the pack more closely to the user, like adjustable torso length, load lifters, bendable stays, adjustable shoulder strap width, and anatomically shaped padding.

For short ultralight trips, the Mariposa Plus simply has too much volume. One solution is to put your sleeping pad inside the main compartment to take up some of the volume. If you use an inflatable pad, you can even partially inflate it to adjust the volume. This technique would allow you to use one pack for practically any application. Alternatively, you could purchase Gossamer Gear’s Miniposa pack (3300 cubic inches, 18.6 ounces), which is about 900 cubic inches smaller.

Gossamer Gear Mariposa Plus Backpack REVIEW - 8
We all loved Gossamer Gear's G4 (left) in its heyday, but its 4600 cubic inch volume was simply too much for ultralight backpacking. The Mariposa Plus at 4200 cubic inches (center) is much better. It’s about the same size as the Six Moon Designs Comet (right), although the Comet has a specified volume of 3700 cubic inches. Volume specifications don’t always indicate the actual size of a pack.

The only other packs on the market with features and weight comparable to the Mariposa are the Six Moon Designs Starlite and Comet. The Starlite (30 ounces) has the same volume as the Mariposa, is constructed of rugged fabric with Dyneema gridstop, has hipbelt sizes available with and without pockets, has load lifters and hipbelt stabilizer straps, and has removable, shapeable flat aluminum stays. It also has a zippered security pocket on the inside. However, it weighs about 10 ounces more and is available in only one size that adjusts to fit a wide range of torsos. The slightly smaller (3700 cubic inches, 27 ounces) Comet has been re-designed for 2007, and has a similar feature set to the Starlite.

A distinct advantage of the Comet and Starlite is their torso length is adjustable and their aluminum stays can be bent to match the curvature of the user’s back to provide a customized fit and more comfort and weight carrying capacity.

What’s Unique

The Mariposa Plus is easily the lightest durable internal frame backpack on the market in its size class. It’s also extremely versatile. With the stays and other components removed, its weight is competitive with many frameless backpacks on the market and it’s more comfortable to carry because of its wide padded shoulder straps.

Recommendations for Improvement

  • Offer hipbelt pockets and a sternum strap pocket as an option or accessory
  • Switch to curved flat stays to achieve a more anatomical fit
  • Sew in the padding in the shoulder straps and hipbelt, and eliminate the Velcro closures
  • Move the sternum strap buckle to one side


"Gossamer Gear Mariposa Plus Backpack REVIEW," by Will Rietveld. (ISSN 1537-0364)., 2007-09-12 03:00:00-06.


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Gossamer Gear Mariposa Plus Backpack REVIEW
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Miguel Arboleda
(butuki) - MLife

Locale: Kanto Plain, Japan
Mari-Mini-Posa Recommendations on 10/21/2007 18:05:39 MDT Print View

Thanks everyone for your suggestions. Carlos... yet it IS difficult to find the perfect pack, but I'm also beginning to feel pack overload with too many things. The more gear I collecct the more difficult it becomes to THINK about going light and keeping things simple. And that I guess means the pack itself must be simple.

Your suggestions have helped me to make a better decision. I'd consider the Conduit but it's not possible to order it at the moment. Besides the GG seems to fit a little better, from all the photos I've seen.

Greg Mihalik
(greg23) - M

Locale: Colorado
Re: Miniposa aluminum stays on 03/07/2008 21:58:31 MST Print View

Way back in September you said -

"I made stays for my miniposa from #1916 easton aluminum arrow shafts. They bend easily with a little heat from a plumber's torch, and the little rounded ends that came in the carbon stays even fit back in the ends. They only weigh 0.4 oz each, and work pretty well."

Do they roll or stay put?
Have they taken a fair amount of abuse?
Did you find anything better?

I think curved stays are the way to go, and if these are still working for you I'll follow suit.

Got any follow-up comments?


Nathan V
(Junk) - MLife

Locale: The Great Lake State
Re:Re: Miniposa aluminum stays on 03/08/2008 07:15:48 MST Print View

Greg, In response to your questions,

1- Yes, they can roll, but usually only when you are packing your gear. If I am careful to make sure they don't spin in the tube while packing, then once you put the pack on they can't spin, because of the fitted shape against your back.

2- They have worked well for me so far. Haven't bent or broken, with about 18 lbs. which is about the max I've carried in it.

3- I've heard GG is working on some curved stays that are connected to each other, so they can't roll. You could try emailing them about those.

I plan on sticking with my homemade stays again this year.

Greg Mihalik
(greg23) - M

Locale: Colorado
Re: Miniposa aluminum stays on 03/08/2008 07:52:42 MST Print View

Thanks for the follow-up. Nothing like field testing to get it right. I'll give it a try, perhaps with a drilled-thru cross-connector

I did email GG and although they are working on the details, they won't be making any changes for the coming year. However, Grant did assure me that anything they come up with will fit prior models as well as the new models.

James D Buch
(rocketman) - F

Locale: Midwest
Carbon Stays Bendable Stays on 05/26/2008 06:16:53 MDT Print View

================== QUOTE ============================

Even if the carbon fiber stays were bendable, I really doubt they can maintain the shape of the pack's back -- given how thin they are. More likely, the two thin tubes will simply twist sideways... giving essentially zero effect.

A pair of bendable stays would need to be flat -- and also wide and strong enough to force the pack's back to conform to the shape of the stays when everything is cinched tight. I think that will be adding a lot of weight to the pack.

If one wants a real frame to add some form and rigidity to the pack -- but not 100% straight up -- then a partial HDPE framesheet plus peripheral fiberglass hoops used by some pack makers may be a better answer then slipping in two metal stays in the middle. Again, just thinking out loud.

================== END QUOTE =======================

Bendable flat aluminum stays could be lightweighted by machining holes into the middle of them. This is the standard traditional aircraft approach to lightweighting aluminum, so it has a good track record - when done intelligently.

More expensive would be to machine or custom extrude/hotroll the aluminum bar to resemble an "I" beam with a thin web and thickend edges. The thin web would lie parallel to the back. This is use of an "I" beam in the transverse direction (at 90 degrees to the normal)and while it provides stiffness at less weight than a flat bar, it isn't particularly structurally efficient.

Still, more thinking might lead to an improved solution.

There are probably inexpensive bending fixtures that one can make at home, with a little thought.

wax wax
(wax) - F
The actual capacity of a Mariposa pack. on 06/16/2008 10:39:33 MDT Print View

Thanks for the tip on the aluminum stays. I just made mine and it does improve the comfort of the pack. About the Mariposa (or Mariposa Plus), I had a question about the capacity of the main pack body.

When measuring the pack (without the extension collar), I get the following numbers:

Height: 20.5"
Width: 10.5"
Depth: 6.5"

This gives ma a capacity of 1400 c.i. If I add the extension collar (13" max), the capacity reaches 2290 c.i.

I know that my model is a "small" and that silnylon does stretch a little bit but the theoretical number I'm getting is quite below the official number of 3700 c.i.

I did ask Grant at Gossamer Gear about this and he said that the pack's capacity should not be computed theoretically but in a practical way (by filling it with packing peanuts for example and then measuring the amount filled). But I'm not really convinced by his reasoning.

Has anybody measured the real volume of a Mariposa pack ? I'm just curious about this discrepancy but I must also add that I am very happy with this pack. The weight / comfort is really amazing.



Edited by wax on 06/16/2008 10:40:14 MDT.

Jim Colten
(jcolten) - M

Locale: MN
Re: The actual capacity of a Mariposa pack. on 06/16/2008 12:55:33 MDT Print View


This link at McHale Packs has an explanation why HeightxWidthxDepth is not a particularily accurate estimate of pack volume. The "Do this fun experiment:" section at the end is a succinct summary.

Edited by sharalds on 06/16/2008 15:28:12 MDT.

wax wax
(wax) - F
The fun experiment on 06/16/2008 15:15:35 MDT Print View

Thanks a lot Jim ! I did the experiment and it's very interesting. Now I understand my mistake about the way I computed the capacity well as the way I packed my bag ! For the moment this isn't a big issue since I don't need a lot of volume but it's interesting to know that by putting my half Z-Rest outside of the bag, I will gain much more than the volume of that half Z-Rest.


Edited by wax on 07/15/2008 01:28:56 MDT.

Keith Selbo
(herman666) - F - M

Locale: Northern Virginia
Canisters and Straps and Pockets on 09/11/2009 08:25:03 MDT Print View

You can add the Bearikade Expedition to canisters that will fit inside this pack. It's the largest canister I know of.

I agree with the commenter who said the sternum strap is too long. I'm thin and I needed to shorten it so I could properly cinch the shoulder straps. Once it was tight enough, the buckle and strap dug into my chest which made me think the strap could be wider too. For now, I put a piece of half inch thick, 3 inch wide closed cell foam under it.

I prefer a waist pack to pockets on the straps. There are things I want to carry when I've doffed the pack.