Reader Reviews

Rating: 5 / 5

I now have a number of seasons with this bag and can now pass considered judgement. I have a long version of the bag when Marmot was claiming down of 900 lofting power (current models use 850) although I can tell no difference between the quality of down used between this and what Western Mtneering uses in it's premium bags.

The Hydrogen is a slim, mean half zippered mummy bag with a superb hood and muff that are comfortable and efficient in sealing out drafts. The stiffened draft tube does a good job of allowing snag free zipper operation. The Pertex Quantum shell is pretty downproof and has a very water repellant DWR treatment. Total weight w/o stuff sack for the long size (up to 6'6") is 23.6oz., 13 oz. of 900 down fill, 4.3 in. total loft, single layer loft of approx. 2.5 in. This is a technical bag made to keep things to essentials---it's not for someone who requires lots of wiggle room, although it will accomadate side-sleepers.

The user has some additional temp. control by shifting down around on the upper portion of the bag due to the continuous baffles there. Below the zipper there is a cross-block baffle to control down distribution. The footbox has a nice efficient size (but not too tight for larger feet) and shape. The bag is rated by Marmot at 30 degrees F and is probably not an overly enthusiatic rating for most users in good shape. Tarp camping with a light bivy, I have had this down in the low to mid 20's and to even lower temps. wearing insulated clothing to bed. The bag is well made as are most of Marmot's high end bags, of a level similar to WM. Retail is about $330 (ouch!) but possible to find at lower prices with judicious shopping research.

Noting it's slim cut, I recommend this bag for ultralight summer season high country use, particularly for those new to UL backpacking and anyone who is uncomfortable with the idea of quilt sleeping (and their learning curve for lower temp. use) and are not aspiring for 5 lb. baseweights.

Edited by kdesign on 06/10/2007 21:45:23 MDT.

Rating: 5 / 5

This is probably the 6th down sleeping bag I've owned, and IMHO the best summer bag on the market.

I have the 2009 version with a full-length zipper - a real improvement.

I carried this bag on the CDT, and slept through several below-zero nights. On cold nights I wore my Patagonia down sweater inside the bag for extra warmth.

I really like the hood - very spacious, but the best part of the bag is really the zipper. It's so solid feeling and reliable without being heavy. Really well done, and the place where this bag excels past anything from Western Mountaineering.

Rating: 5 / 5

first this is a 2009 model as the above poster

I had WM Summerlite, great bag, just too tight for me. The Hydrogen is more roomy for myself (6' 190#). I find the 30 rating to be very accurate- I've had the bag down to this temp several times wearing just light base layers. With insulated clothing you could push this bag comfortably into the 20's. The full length zipper allows you to vent it nicely in warmer temps. The DWR finish is very good also.

My regular length Hydrogen weighed in at 24 oz even, pretty decent weight considering the fuller cut and full length zipper.

The Hydrogen is a solid 3 season performer.

Rating: 5 / 5

I've got an older model with the shorter zipper that weighs 23 oz. I use it with my warm clothing (down jacket, balaclava, long underwear) on the coldest nights. I've slept toasty down into the teens. It's light, compressible, warm and comfortable. I carried it for all of the PCT and all of the Desert Trail and it seems to loft as good as ever.