When I pulled the Hummingbird Gear 65-liter Cargo Carrier (MSRP $79.95) out of its packaging, my first thought was, 'Wow, this is a pretty big pack. Um...what am I going to do with it?'

Constructed out of vinyl and nylon, the bag is made for use in watery conditions. Featuring a padded shoulder harness and a simple waist belt, it is also meant to be worn like a backpack. While the skimpy waist belt is enough deterrent to actively use the Cargo Carrier on a backpacking trip, the bag itself sure makes it easy to tote all your belongings around airports, bus terminals, and worldwide adventures. But in a landlocked desert, such as where I live, what were the best uses for this roomy gear carrier?

Snaking through twisty, potentially wet slot canyons with this waterproof bag was an immediate thought. This hefty 65-liter container is somewhat ambitious for most slot canyons, however, as many of them barely have enough room for a fit human body to pass through, let alone a full pack this size. The smaller 40-liter Wide-Mouth Carry On version might work well in a slot canyon, however.  And the tough material is a great choice for sliding through the abrasive sandstone walls of slot canyons.

Of course, the usual first thought for using a Hummingbird bag would be a river trip. A friend happens to own the exact same Cargo Carrier, and she took it with her on a 10-day Grand Canyon trip last year. Her consensus is a) great river trip bag; b) yes, pretty darn waterproof if you get it rolled shut right; and c) the 65-liter is just shy of being the perfect size for such a lengthy trip.

She had problems, however, shutting the bag when it was filled with her gear. Her best suggestion for a river trip is to use smaller dry bags inside the Cargo Carrier, to both ensure dryness as well as make it easier to find things.

Finally, I simply filled it with gear, strapped it on, and went for a hike. As noted, I wouldn't necessarily recommend the Cargo Carrier for real backpacking. But for a day hike or a stroll through a bustling city, it could do the trick. But it's simply not as comfortable as a pack specifically designed for backcountry excursions, and since it's just one huge bag, with no extra pockets or areas to stuff gear, I found it annoying to have to root through the deep, dark interior to find anything.

Then again, the packaging and website indicate that Hummingbird Gear is slanted toward the world traveler rather than the backcountry adventurer.

The top is a classic fold-down to keep water out. The directions are printed on the heavy nylon strips that stiffen the fold area as well as indicate how to fold it. Once folded down, buckles are in place to snap shut and effectively seal off the interior.

Of course, Hummingbird clearly states “There is no roll-down closure from any manufacturer that is totally waterproof when submerged,” therefore throwing up a thin shield between them and any potentially waterlogged, angry consumers out there. Yet without actually going to the lengths of submerging the filled thing in a body of water, I venture that their design is reasonably waterproof when used correctly. With its overall sturdy design, I felt satisfied that this pack can take plenty of use before wear starts to show. I felt comfortable having my gear stashed in it.

I recommend taking a look at the included instructions on how to strap and snap everything shut. Otherwise, the straps are a mite perplexing on first glance. I attached the wrong straps to one another and sat in utter confusion for a few moments before I reached for the instruction sheet and got an education. Once you have it figured out, though, piece o' cake to remember.

The system works quite well, actually: roll the top shut, snap down the straps along the sides, then snap down the straps that reach over the top of the bag from the shoulder straps. Et voila, you have (in theory) a nicely-rolled and shut pack. You might note from the photo, however, that it doesn't come out looking quite as precise as it does online. That's the real world, folks. But it does work.

Bottom line: Best for river trips or any other adventure in which your gear needs to stay dry.