Few pieces of gear annoy me more than the duck's back—a nylon cover necessary for keeping packs waterproof. Shouldn't packs already be waterproof? Some high-end brands (like Arc'Teryx) are solidly water-resistant, but if you buy a mid-priced pack, you'll likely get a below-drinking-age sales rep at your local outdoor store haggling you to buy a duck's back or "you'll be sorry." If you skip it, you won't be—until you get caught in a real mountain downpour and find your insulation layers wetter than a used dishrag.
After a wet summer spent under frosty downpours in Canada, the Tetons, New Mexico, and Glacier, I got my hands on Mammut's Trion Lite ($199.95), a lightweight, waterproof mountaineering pack set to debut in 2010. Besides being seam-sealed on the lid and at the base, the Trion has a removable waterproof liner; it's like zipping a dry bag inside your pack. (Mountaineers who want to go lighter and expect dry climes can unzip and ditch the liner if they choose.)
On a test outing up Blanca Peak in the Sangre De Cristo mountains of Colorado, the forecast called for sunny skies, so I thought I might escape rain for once (good for me, bad for pack testing). Of course, Mother Nature was toying with me: An overnight thunderstorm on my first night dumped hail, rain, and graupel on the Trion, which I'd left out in the open. My morning rummage revealed that extra socks, baselayers, and even paper notepads stayed bone-dry.
Testing the Trion on Blanca Peak.
On trail, the liner doesn't add too much noticeable weight, nor does it interfere with the pack's close-to-the-back design, which hugs your hips and back while balancing on precarious terrain. This came in handy as we climbed Blanca's upper slopes: The last night's storm coated the final approach of sharp talus in rime ice and filled the faint trail with slick, wet snow. At around 13,500 feet, our faces frosted with freezing mist from the surrounding clouds, but nothing penetrated the Trion Lite. One summit later and even my dry snacks were crispy—amazing considering the dismal conditions.
Short of throwing the pack in the river, the Trion Lite seems to deliver as promised without compromising its efficient, alpine-ascent style design. The compact inside won't hold much more than a weekend's worth of stuff, and the lack of side zippers or alternate entry points can make rummaging through the pack a pain, but so far the Trion hits all the high notes.
Right now, BP testers have the Trion Light in even rougher, possibly wetter locations. Make sure and check back in April to see if the Trion Light makes the cut for our annual Gear Guide.