Marmot Hydrogen Review

Performance Comparison

The Hydrogen is lightweight but narrow. That makes it ideal for shorter backcountry missions where its constrictive feel won't have time to become too unbearable.

Photo: Jack Cramer

Warmth

Marmot leaves a nice buffer between the Hydrogen's advertised and tested temperature rating. They market it as a 30° bag while it receives a 23°F rating on the industry-standard EN test. As you might guess, our testers think it feels a little warmer than its advertised rating. It supplies this warmth with 13 oz of 800 fill power down, which is a decent amount considering the bag's narrow dimensions.

Despite the introduction of EN ratings, companies still chose the temp rating they market a bag at. Marmot leaves a nice buffer between the Hyrdogen's EN lower limit rating (23.4 F) and its marketed rating (30 F).

Photo: Jack Cramer

Weight

At 1.73 lbs for size Long (which we tested) and 1.4 lbs for size Regular, this bag is slightly ahead of the field in terms of weight. When you factor in its above-average warmth, it equates to an overall above-average warmth-to-weight ratio. This is surprising if you consider that the Hydrogen provides roomier dimensions and some additional features you won't find on other light bags that are fully optimized for minimum weight.

Cowboy camping under the stars is always a treat, but be wary of rain or dew with a down-filled bag like the Marmot Hydrogen.

Photo: Jack Cramer

Comfort

One of the ways the Hydrogen achieves its impressive warmth-to-weight ratio is through its narrow dimensions. With 61 inches of shoulder girth, the upper body section of the bag actually supplies adequate space. The same cannot be said as the bag tapers toward your feet. The footbox, in particular, feels uncomfortably constrictive. We also heard complaints about the drawcord used to seal up the hood. It's flimsy with a pointy melted tip that had a habit of floppy around and scratching our testers faces.

The svelte Hydrogen can compress impressively small. The included stuff sack, however, isn't designed to achieve maximum compression.

Photo: Jack Cramer

Packed Size

Considering this bag's near average weight, it performs impressively well when it comes to packed size. With the help of an aftermarket compression sack, we were able to squeeze it down to 6.8L, which is just fractions of a liter more than the smallest 3-season sleeping bags we've tried. The stuff sack it comes with, however, is of the simple drawstring variety so if you hope to enjoy the super small packed size we observed, you'll need to buy a third party compression sack.

This bag is distinguished by its 14-inch auxiliary zipper, seen here on the left, which lets you shed heat better on a warm night.

Photo: Jack Cramer

Versatility

To boost your options for venting excess heat the Hydrogen is fitted with a 14-inch auxiliary zipper positioned opposite the main zipper near the head of the bag. When opened, this allows you to fold down the collar and let your neck and upper chest breathe. It's a nice feature, but we're not fans of the tiny zipper it relies on because it's so prone to snagging.

There's a small zippered pocket inside the bag to keep your battery-powered electronics warm. This iPhone X barely fits inside.

Photo: Jack Cramer

Features & Design

Inside the bag is a slim zippered pocket that's just large enough to stash an iPhone X. The main zipper incorporates a Y-shaped slide that's designed to reduce snags. We found it to be modestly successful at this goal.

We're not happy about the hood drawstring made of supple string because it often dangles down to irritate your face. We also dislike that the useful accessory venting zipper is sewn fully into the bag which makes it a serious chore to fix if it becomes misaligned.

The main zipper is an effective Y-shaped design but the adjacent fabric is supple, rather than stiff, and susceptible to occasional snags.

Photo: Jack Cramer

Value

This bag retails near the average for a 3-season backpacking sleeping bag, and it's been around long enough that we occasionally see it on sale. At full price, we consider it an OK value, but there are a few other bags priced competitively that we like a little more, such as the 850 fill power REI Magma 30. If you're able to find the Hydrogen at a decent discount it could still be worth considering.

This auxiliary zipper on the Marmot Hydrogen boosts the bag's versatility, but its sewn fully into the bag. That means if it gets misaligned there isn't a easy way to fix it.

Photo: Jack Cramer

Conclusion