Marmot Helium 15 Review

Marmot is experimenting with adding a secondary zipper to several sleeping bag designs to allow new venting possibilities. The location of the secondary zipper on the side of the Marmot Helium 15 is one of the more perplexing of these experiments, causing us to downgrade an otherwise stellar sleeping bag.

Performance Comparison

Warmth

The Marmot Helium utilizes 20 ounces of 800FP down, a pretty sizeable amount for a 3-season backpacking sleeping bag. It receives a 10F lower limit temperature rating on the industry-standard EN test but Marmot markets the bag with a more conservative 15F rating. We think the conservative manufacturer rating is more accurate because this bag doesn't incorporate a neck baffle to trap heat inside the bag. Some folks may prefer the simplicity of this design but be aware that this allows considerably more heat to escape out the collar of the hood. This isn't an issue in most conditions but it becomes a problem in temps approaching the 15F rating.

Weight

A size long Marmot Helium weighed in at 2.08 pounds on our GearLab scale. That's pretty light for most backpacking sleeping bags with this level of warmth. However, the Helium is a premium bag with a premium price. In our tests, we identified a couple of other bags that provide similar warmth while weighing as much as 25% less. So even though the Helium is light, we were disappointed with its warmth-to-weight ratio compared to the top-performers in the category.

Comfort

The comfort of the Marmot Helium is enhanced by its generous upper body dimensions. Unfortunately, it tapers considerably at the foot box and some of our testers found the narrowness in this area unpleasant. We did like the supple feel of the 30-Denier nylon lining combined with its fluffy 800FP down. The hood also seems well thought out with a spacious design that can cinch comfortably to seal heat in on a cold night.

Packed Size

As one of the warmest models in our backpacking sleeping bag category, the Marmot Helium 15 includes substantially more insulation than others, and its packed size understandably suffered for this reason. Although it's a bit bulky, the premium down is still highly compressible and we would estimate that it would exhibit a better than average packed size among bags supplying similar warmth. Although this bag comes with a drawstring stuff sack, we discovered that it was exceedingly difficult to stuff our size long test model inside. We do not know if the same issue would occur with a size regular.

Versatility

One of the unique features of the Marmot Helium is a secondary zipper on the right side. The intention is that you can open this zipper to vent excess heat on warm nights. In practice, however, we found it rather ineffective for this purpose. The secondary zipper is simply too short to open the bag very far. On colder nights, the Helium also seems to be ill-designed because it lacks a neck baffle to seal heat it. Due to this issue, we think this model has a rather narrow usable temperature range and it's thus not very versatile.

Features & Design

One of the best features on this bag is the hood which cinches down comfortably and incorporates a drawcord that's directed away from your face. The bag also includes a convenient stash pocket for keeping the batteries on a headlamp or small smartphone warm. When it comes to the broader design, we just can't get past the ineffectiveness of the secondary zipper. We believe using the extra zipper material to extend the main zipper from 3/4- to full-length would improve versatility far more. The bag could weigh the same and a truly full-length would allow it to unzip into a blanket for warm nights.

Value

The Marmot Helium 15 is a high-end sleeping bag with a corresponding price. Its 800FP down certainly feels premium and we were impressed with its all-around construction. When you compare the Helium with other high-end models, however, its deficiencies become apparent. Other companies simply offer lighter, more packable designs that also utilize even loftier down. If you're going to splurge for an ultra-premium sleeping bag, the Helium seems like a subpar value.

Conclusion