Nobody at Sierra Designs promised DriDown to be waterproof, to make all our dreams come true of having the lightest, most packable, best-insulating material we’ve yet discovered—down—overcome its one drawback, which is its complete inability to insulate once it gets wet. But could their treated down handle at least some moisture, the incidental water we encounter hiking through rainstorms, condensation, and humid environments?

The claim is that DriDown will stay drier longer than untreated down, thus keeping you warmer, and that it will dry out a third faster than regular down, which could be cool on multi-day trips when it gets a little wet.

The three main times I’ve had problems with regular down sleeping bags have been:

• Sleeping with no tent next to a body of water (river, lake, ocean) and waking up freezing because the increased humidity/water in the air has soaked through my sleeping bag.
• Sleeping in a bivy sack and waking up freezing because condensation has gathered on the top of the inside of the bivy sack, soaking the top of my sleeping bag.
• Sleeping in a small mountaineering tent and waking up freezing because condensation has gathered on the walls of the tent, soaking my sleeping bag wherever it’s touched the walls.

Since February, I’ve tested the Zissou in all three situations — on an April climb of the Mountaineers Route on Mount Whitney, a shoreline campsite on a sea kayaking trip, and car camping in a bivy sack, and had no problems. Where in the past I’d woken up with cold feet in the middle of the night because of wet down in the footbox of my bag, I was toasty in the Zissou.

The 15-degree Zissou weighs in at a competitive (for a 15-degree bag with 600-fill down) 2 pounds, 11 ounces. DriDown is also used in 0-degree and 30-degree versions of the Zissou, as well as two women’s bags called the Eleanor in 20- and 30-degree models. Jackets with DriDown will be available starting August 2012.

$260 LINK