The Gossamer Gear (formerly GVP Gear) Mariposa represents a significant step forward in the ultralight backpacking industry; a 1-pound (0.5 kg) pack capable of carrying loads up to 30 pounds (14 kg) in reasonable comfort. Gossamer Gear does this without losing features like full peripheral pockets, padded hip belt, bear canister compatibility, and an ice axe loop (Photo 1).

The key to this carrying capacity: two carbon fiber stays combine with the hiker’s sleeping pad to form a rigid frame that effectively transfers pack weight to the hipbelt. Another innovation is the use of pad pockets on the shoulder straps and hip belt that permit exchanging the included closed cell foam pads with articles of clothing, thus leaving the padding weight at home. Further weight is reduced by the use of 1.3 oz/yd2 (44 g/m2) silnylon for most of the pack body (oxford cloth is used in key stress/wear areas). Obviously, a pack made of such lightweight material is not designed to handle the rigors of off trail backpacking and climbing. One gripe: the harness on the prototype Mariposa tested was not a great fit. We’ve talked with Gossamer Gear and expect a few tweaks will significantly improve comfort on production packs.


  • Backpack Style
  • Internal frame, top-loading pack with roll-top closure

  • Fabric Description
  • 40d 1.3 oz/yd2 (44 g/m2) silnylon and selected use of 210d 4 oz/yd2 (136 g/m2) urethane-coated ripstop nylon

  • Sizes (Size M tested (prototype))
  • Sizes Torso Length (in) Torso Length (cm)
    S 16-19 41-48
    M 18-22 46-56
    L 20-24 51-61

  • Volume (Size M tested (prototype))
  • Sizes Volume (ci) Volume (L)
    S,M,L 4,200 69

  • Weight (Size M tested (prototype))
  • Component Measured
    Weight oz (g)
    Manufacturer Specification
    Weight oz (g)
    Pack complete 17.0 (482) 17.4 (493)
    Pack stripped 14.9 (422) 14.6 (414)
    Stays 0.9 (26) pair 0.8 (23) pair
    Hip belt pads 0.3 (9) pair 0.4 (11) pair
    Shoulder pads 0.4 (11) pair 0.4 (11) pair
    Sternum strap 0.5 (14) 0.5 (14)

  • Volume to Weight Ratio
  • 247 ci/oz size M (Based on 4,200 ci, size M, and Backpacking Light measured weight of 17.0 oz)

  • Load Carrying Capacity
  • 30 lbs (13.6 kg), maximum comfortable carrying capacity as determined by Backpacking Light.
    Manufacturer claims 40 pounds (18.1 kg) maximum carrying capacity and Backpacking Light agrees the Mariposa will carry it, but with reduced comfort and with greater concern for fabric failure.

  • Carry Load to Pack Weight Performance Ratio
  • 28 (based on 30 lbs and Backpacking Light measured weight of 17.0 oz)

  • MSRP
  • approximately $140, price not set at time of review

  • Manufacturer’s Contact Information
  • Gossamer Gear, 877-ULTRA-LT, http://www.gossamergear.com


    Ratings follow subtitles on a scale of 1 to 5, with 5 being the best, and are relative to other Backpacking Light tested internal framed packs.

    Frame and Suspension – 3.5 (pre production) 4.0 (if production changes made)

    Gossamer Gear’s Mariposa uses an innovative frame and suspension setup to comfortably carry loads up to 30 pounds (13.6 kg) in a pack weighing just a shade over 1 pound (0.5 kg). Currently, only two other pack manufacturers are employing similar frame designs (Six Moon Designs Starlite and ULA Fusion). The Mariposa integrates the user’s sleeping pad with two hollow carbon fiber frame stays to create a rigid back panel. The pack’s pocketed back panel has an opening slit in the center, where a sleeping pad is inserted, first into the bottom half and then into the top. Most thin 3/4-length closed cell foam (i.e. RidgeRest or Z-Rest) or any length rectangular, self-inflating pads should fit. This pocket measures 11 inches wide by 20 inches high (28 x 51 cm). If a self-inflating pad is used it has to be inflated before inserting, as there is no opening in the pocket to gain access to the valve. Inserting a sleeping pad into this pocket is slightly cumbersome, but the design is extremely light and simple.

    The two carbon fiber stays look similar to carbon arrow shafts, but are nicely finished on both ends with a dome-shaped aluminum cap. The shape and smoothness of the caps prevent inadvertent fabric wear within the stay sleeves; an important consideration in such a light-fabric pack. The stays are easily removable by opening the Velcro closure at the tops of each stay pocket. It is not possible to reshape them, though the sleeping pad tends to conform to one’s back shape to some extent.

    The back panel/pad pocket material is mesh. This material is thin and the portion of the sleeping pad, between the upper and lower sleeves is directly against the user’s back. The type of sleeping pad selected will determine pack comfort while on the trail. Closed cell foam pads that contain ridges and valleys offer some additional breathability over the self-inflating types, a relief when hiking in hot weather.

    The Gossamer Gear’s harness sets it apart from most lightweight packs. Upon first inspection it appears simple, but this belies a sophisticated design. You can use gloves, socks, or other articles of clothing to replace the closed cell foam inserts (included) in the shoulder straps and hipbelt. This saves the weight of the foam padding and even gives you some extra pack room.

    the harness
    Photo 2: The Gossamer Gear Mariposa shoulder straps require something inserted into the shoulder pad pockets in order to maintain their full width and comfort. Shown here, the pad on the right (subject’s left) contains a thin polypropylene balaclava. The strap on the left is empty.

    The Mariposa has a removable sternum strap with a safety whistle. Both the shoulder straps and hipbelt are sewn onto the back panel. Thus, the harness does not adjust to accommodate varying torso lengths. It also lacks shoulder strap and hip belt stabilizers. Unnoticed initially are Velcro openings along the seams of both the shoulder straps and hip belt, which allow the user to remove the padding to save weight. My first unfounded concern was that my clean socks were going to get soaked with sweat before I had an opportunity to wear them. However, a layer of 1.3 oz/yd2 (44 g/m2) silnylon lines the inside of these pockets to keep the contents dry. In addition, the shoulder straps are a whopping 3.5-inches (9 cm) wide at their contact point. With lighter loads, many users will find the padding unnecessary. I was also concerned that articles of clothing used to replace the closed cell foam would not provide enough padding for comfort. Because the shoulder pads are so wide, the “padding” need only spread out the shoulder straps and keep them wide (Photo 2). In our testing, a shoulder strap without any padding would curl and become narrower, concentrating the pack weight on a smaller area and increasing discomfort. However, with as little as a thin polypropylene balaclava, the straps would maintain their full width and evenly distribute the load. Care must be taken to insert and remove clothing items without snagging them on the Velcro openings. You can also put the item in a light baggie to solve this problem and keep the article extra dry.

    The fit was not perfect with our “pre-production, prototype” Mariposa. While the fit of the prototype will be discussed here, we have spoken with Gossamer Gear to learn others have expressed similar concerns with the prototypes and production runs will be corrected. With that said, the hip belt is sized fairly large on the size Medium prototype tested. With the padding removed, the hip belt was too big for my 33-inch (84 cm) waist. Even with the foam pads inserted, the adjustment straps would bottom out before the hip belt was completely snug. Production runs will have a slightly shorter hip belt (padded portion), which will alleviate this concern. Also, the webbing that the sternum strap adjusted on was too high. Referring to Photo 2, the sternum strap is at the bottom of the adjustment webbing, which is attached to each shoulder strap. Notice that the strap is well above the center of the wearer’s chest with nowhere to adjust but up to the neck. Again, production models should be corrected in this area.

    Usable Features and Ease of Use – 4.0

    Even at 17.0 oz (482 g), the Gossamer Gear Mariposa is still a full-featured pack. It has a total of four external nylon mesh pockets, not including the pad pocket and harness padding pockets. The pockets serve two purposes-to provide convenient storage and retrieval of frequently needed items and to protect the lower portion of 1.3 oz/yd2 (44 g/m2) silnylon making up the pack body. The lower back is covered with a large pocket suitable for storing wet tarps and the like. On the left side panel, a long 13-inch (33-cm) pocket provides enough room for a 2-liter water bladder. There are two pockets to protect the right side panel, one above the other. The lower 1-liter water bottle pocket is easily accessed while wearing the pack. A thinner map and compass sized pocket is above that.

    The pre-production sample received for this review did not include the internal hydration pocket that will be found on production models. The hydration pocket will be constructed out of 1.3 oz/yd2 (44 g/m2) silnylon, be non-removable, and will include two drinking tube ports. Since it is going to be made of silnylon, we don’t expect it to add much weight (approximately 0.2 oz, 6 g).

    The back pocket is covered by a removable shock cord, which provides some minimal compression and an additional location for storing wet gear. The shock cord is laced through grosgrain attachment points located along both vertical seams on the back. These attachments points are repeated down each vertical seam on either side of the back panel, at the front of the side panels. These offer additional gear securing options and because they are tied into the 210 denier nylon oxford fabric, they are a more durable attachment point. These can be used to attach the tops of long items (trekking or tent poles) that are inserted into the side pockets, as an additional location for compression shock cords, or as a convenient location for one’s bandana or towel. Use your imagination.

    For those who like to venture over ice and snow, a single ice axe loop is centrally located below the large back pocket. It could also be used as a place to attach adjustable trekking poles. When the back pocket is full, items attached to this loop are pushed away from the pack by the pocket contents. Attachment for other climbing hardware is not provided. A single haul loop is included between the shoulder straps.

    The top of the Mariposa closes like a stuff sack, with a draw cord closure. The top of the pack is then secured with a Y-shaped compression strap. This grosgrain-webbing strap attaches at the top of each shoulder strap and extends all the way to the bottom of the large back pocket. In addition to compressing the pack, its wider profile across the top provides storage for larger items, like a bear canister, that might sit on top of the pack.

    Load Volume Flexibility (Compression) – 2.5

    The Gossamer Gear Mariposa can adjust to varying volume loads, though this is not its strong suit. To adjust to smaller loads, the contents initially stored in the mesh exterior pockets can be brought to the inside and the single top compression strap tightened. This, combined with tightening the back shock cord, is the only means of converting this pack to daypack dimensions. Heavier items will tend to stretch out the shock cord rendering compression less effective. Because of the limited number of compression straps, the fully compressed Mariposa looks lumpy. Very small volumes do not compress well to the point of having loose contents in the pack. Larger loads that exceed the pack body’s 2,900 cubic inch (48 L) main volume, can overflow into the 500 cubic inch (8 L) mesh pockets and 800 cubic inch (13 L) extension collar, with the remaining gear attached using various shock cord arrangements, before resorting to hand carrying gear.

    not full
    Photo 3: The Gossamer Gear Mariposa, fully compressed, on a return trip from collecting water. One can see some limitation in the compression system for small dense loads.

    Field Performance

    Pack Load Carrying – 4.0

    The Mariposa was tested while carrying weights ranging from 15 to 40 pounds (7 to 18 kg). We tested it both properly loaded approaching full volume, and with small volume, dense loads (i.e. water hauling trips). Although Gossamer Gear rates this pack as able to carry 40 pounds, we find this weight pushes the limits of the Mariposa. Here we evaluate the comfort of the different suspension components, as some hikers will have higher tolerances for discomfort in different areas. With the foam padding inserts, the shoulder straps and hip belt can comfortably carry up to 35 pounds (16 kg). It would seem replacing the foam padding with articles of clothing would greatly reduce the carrying comfort. Actually, the wide 3.5-inch (8.9 cm) straps dissipate the pack weight so well they only need enough “padding” in them to maintain their wide shape. Thus, with articles of clothing filling the shoulder straps and hip belt, we feel they are still comfortable supporting pack loads of up to 35 pounds. The frame stays remain solid up beyond 40 pounds and are not contributors to discomfort. Although the frame stays remain stiff at 40 pounds, the sleeping pad does not. Beginning at 30 pounds (14 kg), and after several miles, we find the sleeping pad within the Mariposa’s back panel collapses a bit and bulges in a way that does not complement the shape of one’s back. While we found it uncomfortable, it was not a level of discomfort that made carrying the pack miserable. It is appropriate to state that the Mariposa is capable of carrying weight upwards of 40 pounds for short legs of a trip where extra water or food is needed. Nevertheless, we found this pack performs best with weights at or below 30 pounds.

    The Mariposa does not have a compression system that fully compresses and controls small, heavy loads. This pack’s ability to stabilize this type of load was exceeded at weights above 15 pounds (7 kg). Therefore, while short trips for water are acceptable with this pack, using it as a daypack or for a summit push may not be appropriate. Gossamer Gear did not design the Mariposa with carrying small, heavy loads as a requirement.

    Durability – 2.0

    A tradeoff with most lightweight packs is fabric durability. Gossamer Gear’s Mariposa is no exception; however, design elements are in place to minimize the 1.3 oz/yd2 (44 g/m2) silnylon fabric from exposure to fabric destroying elements. Both the bottom and back panel of the Mariposa are covered by the relatively more durable 210 denier coated oxford. These areas are exposed to abrasion from the ground and fabric stress from the harness and internal stays. The silnylon, which is used for both side panels and the back, is partially protected by the nylon mesh pockets from the bottom of the pack up to 13-inches (33 cm) high. Assuming these pockets are completely empty, the silnylon can possibly be damaged through the mesh but to a limited extent. The real vulnerable areas are on the upper back and side panels above the 13-inch high pockets. Low branches can wreck havoc on the upper end of this pack.

    This pack is not well suited as a climbing pack or for off-trail bushwhacking. Frequent contact with rock, trees, and other abrasive surfaces will eventually cause fabric failure. This was not the intended purpose of the Gossamer Gear Mariposa, which was designed to meet the needs of long distance trail hikers interested in reduced weight. If you are looking for a lightweight climbing pack, this is not it.

    Value – 3.5

    Considering the weight of the Mariposa, you don’t get much for your money, and we like that. Although higher priced than most silnylon packs, the price reflects innovative design and quality construction. You probably won’t find another 1-pound pack with the features of the Mariposa that can comfortably carry 30 pounds or more. The Mariposa value was slightly downgraded due to its lower durability; though this is the tradeoff for its reduced weight.

    Recommendations for Improvement

    When the back pocket is filled with gear and bulges out, trekking poles or an ice axe attached to the centered ice axe loop at the bottom of the back pocket tend to stick out rather than ride close to the pack. Relocating the ice axe loop to either side of the back would fix this problem. We also expect to see corrections to the hip belt (which was too long) and the sternum strap (which was too high) when full-production packs hit the market. We do not wish to see any improvement to durability, as this would also increase the weight. There are plenty of light, durable packs on the market. The incredibly light, not-so-durable Gossamer Gear Mariposa is a needed extremity to satisfy those on the lightweight fringe who spend most of their time hammering out long miles on the trail.