Hydrophobic, Fully Recyclable Down Sleeping Bag: NEMO Coda Endless Promise Review

There is something indescribably cozy about being curled up in a warm sleeping bag when it’s cold out. I was doing that in the back of my truck, watching raindrops run down the window outside, comfortably swaddled in my NEMO Coda Endless Promise Mummy Sleeping Bag.

It was 8:00 a.m. Temps were probably approaching the mid-40s now, but that night, it had easily dipped into the 30s at Twin Lakes, Colo. I would have been fine if it had gotten even colder. My bag was rated down to 10 degrees (20-degree comfort) — overkill for most summer camping trips, but there had been a couple of cold snaps where I’d been glad to have it.

This particular morning was one of them. But this bag isn’t just warm; as part of NEMO’s “Endless Promise” line of sleeping bags, the Coda represents NEMO’s first fully recyclable line of down bags. It uses ALLIED Feather + Down’s (AF+D) 100% ethically sourced and traceable down. And, when the bag reaches the end of its useful life, AF+D will remove the insulation and reuse it. And NEMO will recycle the rest of the bag’s mono-polymer components.

That novel concept was the hook that reeled me into testing this bag. I’ve been using the Coda from late spring through summer and will continue using it into fall. It’s still many years from being recycled. But recyclability aside, this ultralight sleeping bag is a solid, well-designed piece of gear.

In short: The NEMO Coda Endless Promise Down Mummy Sleeping Bag is one of the brand’s first fully recyclable ultralight down sleeping bags. It comes in two temperature ratings — 10-20 and 25-35 degrees (limit-comfort) — it packs easily, and the hydrophobic down will retain some insulation properties even if water gets past the DWR coating of the shell and liner. The Coda also represents the first generation of NEMO bags using AF+D insulation that is fully traceable and reusable. When this bag reaches the end of its life, and you can send it back to NEMO, and the brand will recycle the entire thing for you.

If you want to compare the NEMO Coda to other ultralight sleeping bags, check out GearJunkie’s guide to the Best Backpacking Sleeping Bags.

NEMO Coda Endless Promise Sleeping Bag Review

GearJunkie reviewed NEMO’s first Endless Promise Sleeping Bag, the Forte, when it was released in 2023. That bag uses synthetic insulation and is completely made of recyclable polyester materials.

Endless Promise recyclable down sleeping bags are a new lane for NEMO, though. It partnered with AF+D to be the first brand to use its innovative down recycling program in 2024.

When Endless Promise down bags are recycled, AF+D pulls the ethically sourced insulation out and funnels it into its RENU:TRACE program. RENU:TRACE uses it to make what it claims is the world’s first fully circular and traceable recycled down insulation. 

NEMO can then break down the bag’s other components and turn them into polyester yarn. It uses that to make its Endless Promise backpacks.

It’s the first time people won’t have to choose between “ethically sourced down” or “100% recyclable synthetic” insulations. They can get both in a single bag. That’s why the Endless Promise line of down bags recently won the Green GOOD DESIGN award for sustainability in design.

Overview

Some people don’t like mummy-shaped sleeping bags. I find them comfortably confining, and they’re my preference for backpacking. So I was excited to see an ultralight down mummy sleeping bag from NEMO.

Some people might knock it for being a darker color, as brighter colors are better for visibility in an emergency. But I won’t. I like the understated “Midnight Gray” NEMO used.

One of my favorite features of this bag is the Thermo Gill vent. It has an inside zipper and an outside zipper that helps control the temperature. If I was overheating, I could open one or both of the zippers all the way or just partially and really dial where I was most comfortable.

The center zipper is also good for ventilation. I opened it as well as the Thermo Gill on a couple of the warmest nights. It only runs about two-thirds of the way down (like most mummy bags), so don’t expect to use the Coda as a quilt. There is, however, another zipper at the very foot of the Coda. Open that up for extra ventilation or to put on/take off socks.

The hood is generous, and a cozy internal draft guard keeps cold air from sneaking in around your neck and shoulders. A hood cinch pulls the hood snugly and evenly around your head and face.

The Coda bag’s shell and liner are coated with DWR for water repellency, and the PFAS-free, RDS-certified 800 FP down is itself hydrophobic. That means that water has a hard time getting to the insulation, and even if it does, the down will retain its loft and insulating properties (to a point).

In the Field

Warmth & Weight

I tested the Coda Endless Promise sleeping bag on several overnight camping trips, a 4-day horseback hut-to-hut trip, and a 3-day backpacking tip — all in the Colorado Rockies in spring and summer. On the cold end, temps got down to the 30s at night. On the high end, nighttime temps hovered in the 50s.

The 10-20-degree bag was too hot for most of these conditions. But in spring and late summer, I welcomed the warmth. It will be even better suited as fall and winter settle in.

If you primarily camp in the summer, the 25-35-degree Coda would be a better option.

Weight-wise, the NEMO Coda is suitable for backpacking. Compared to those on our Best Backpacking Sleeping Bags, the Coda lands on the heavier end of the spectrum, with only four bags weighing more.

I never found the Coda’s weight to be an issue, but I’m also admittedly not a dedicated gram counter.

Vents & Features

The Thermo Gill is a nice feature that I used frequently. I almost never had it completely closed. But I fiddled with different combinations. I unzipped the outer zipper all the way and the inner halfway. Or, I’d have the inner zipper up and leave the outer unzipped completely. It did give me nuanced control of how much heat I was dumping.

Footbox zippers always earn a sleeping bag points in my book. They’re extra ventilation and allow you to walk around in the morning, still wrapped up in your bag. I like popping on a pair of slippers with my bag on and drinking a cup of coffee when it’s still early enough to see my breath. You can do that in the Coda.

However, the tapered mummy shape and relatively short zipper opening mean you’ll be shuffling around more than “walking.”

The hood on this bag is large and easy to find. Between the draft collar and the cinch system NEMO used, you can almost entirely encase yourself in this bag. For very cold evenings this fall and winter, I anticipate those will be very welcome features.

Carbon Questions

I will preface this section by saying that more outdoor gear should be recyclable. Innovating systems and partnerships to make that happen is the only way to move the industry in a more sustainable direction — even if it means balancing carbon costs.

Recycling an endless promise down sleeping bag undoubtedly generates some level of carbon. Plus, customers have to ship the bag back, and AF+D has to remove the down. Finally, NEMO has to send the other components to a recycler that can make new polyester yarn out of what’s left.

How does all that compare to the carbon cost of just making a new sleeping bag?

When we asked NEMO, it said that 87% of its greenhouse gas (GHG) emissions occur before a product leaves the factory.

“Reverse transportation is a minimal part of our overall carbon footprint as a brand. But it is captured in our annual GHG accounting process,” the brand said.

Regardless, the Endless Promise line of sleeping bags from NEMO represents a big step toward sustainability. Recycled bags will keep some plastics out of landfills and allow for the reuse of down insulation. And, as with all technologies, the capital and carbon costs of the recycling process will come down over time.

Room for Improvement

I only had one real gripe with the NEMO Coda Endless Promise Down Mummy Sleeping Bag: the zippers. I get it — NEMO is creating an ultralight product that’s fully recyclable. There were probably only so many zipper designs that fit the bill.

But I had almost constant issues with the zippers (especially the main center zipper) catching on the shell or liner material. Almost every time I zipped or unzipped this bag, I’d get only part of the way down, and it would get stuck.

On a few occasions, when I woke up bleary-eyed and still half asleep to use the bathroom, that was a frustrating problem.

Eventually, I did tear a hole in the sleeping bag because of this issue. When I asked NEMO about it, the brand’s head of customer service said it had never come across their desk. They told me that the brand rarely gets warranty/repair tickets for the Coda.

Maybe I’m just hard on gear. Maybe you won’t have this issue. But if you do, and you rip your bag, I fixed the hole in mine easily with some repair patches.

Editor’s note: NEMO contacted me following this review. It said that this zipper tear issue is limited to pre-production samples of the bag. It said, “We’ve addressed the zipper snag on Coda in the production model with an improved anti-snag reinforcement on the draft tube.“

NEMO Coda Sleeping Bag: Who Is It For?

If you are in the market for a backpacking sleeping bag and you are an eco-conscious person who values sustainability, you should check out the NEMO Coda. It’s a solid sleeping bag designed by a respected brand that’s innovating fully recyclable outdoor gear. That is cool. I wish more brands were putting that much effort into being green.

Even if sustainability is not a priority for you, and you just want a well-designed backpacking sleeping bag, I still recommend at least considering the Coda as a comparison as you shop. This bag — minus all of its sustainability — is still a very strong product. The water resistance inside and out, hydrophobic 800 FP down, ventilation options, and heat-trapping capability make this a powerful contender among comparable bags.

I’ve enjoyed using the Coda this summer. I might even throw it in my pack for a few overnight hut skis this winter. Despite my disagreements with the zipper, this recyclable down bag impressed me. It’s earned a spot in my shoulder-season backpacking kit.