One Planet’s New Cocoon -11°C Down Sleeping Bag – Reviewed & Tested

Light and warm, with a waterproof Storm Foot, the Cocoon sleeping bags seem made for Aussie conditions. Which checks out, One Planet designs and fills the bags in Melbourne.

As long as I can remember, I’ve had cold feet while I’m in a sleeping bag. It didn’t matter if I was toasty warm everywhere else, if my mat had a sky high R value, or I was wearing thick wool socks, my dogs would feel like they were in a crisper, particularly my toes.

‘We can fix that’ Ben from One Planet told me, as he ran me through the specs of their new Cocoon sleeping bag.

The Cocoon, so-named for its cosy hood and – I assume – potential for metamorphosis, is a lightweight down hiking and backpacking bag that comes in three lower limit of comfort temperature specs: -5/+1°C, -8/-2°C, -11/-4°C.

If you’re not familiar with the term; ‘lower limit of comfort’ is the lowest temperature where you’ll be in ‘thermal equilibrium’ while sleeping. A testing protocol called ISO 23537-1 comes up with these numbers based on a fit and healthy, well-fed 25 year old, wearing heavyweight thermal layers including an insulating cap, on a sleeping pad with an R Value of 5.38 (so basically, the ideal scenario). Different temperatures are given for men and women.

Me? I sleep cold and generally don’t tick all those boxes, so I often look for guidance in the women’s rating. Hence, I grabbed the -11/-4°C bag for this test.

I tested the Cocoon in the tail end of winter in the Blue Mountains, before it got far too hot to even think about it for a few months

Why am I the right person to do this review?

I’ve been hiking, camping, paddling, and bikepacking since I was a Cub Scout. I broke my arm on the first day of my first camp, and from there I was hooked. I’ve done treks, ski tours, week long Army Cadet tactical exercises, mountaineering expeditions, and managed an outdoor store.

I’ve seen and felt a lot of gear, including the humble sleeping bag and I’m pretty confident I know both the market, and what I’m looking for. I’m a strong believer that Australian conditions have their own quirks that make local reviews essential, and allow local brands to excel, so I was quite excited about the Cocoon making its way into my gear cupboard.

A cheeky shot of my favourite cafe

One Planet Cocoon Quick Specifications:

Shape: Mummy with box foot
Weight: 932g
Insulation type: 800+ loft DWR-treated ethically-sourced down
Material: 10D Vapour Vent V2
Size options: Small, regular or Large
Compressed size: 19x22cm
Stuff sack size: 8L
Temperature rating (men): -11°C
Temperature rating (women): -4°C
Temperature rating (extreme): -28°C
Zip side: Left or Right
RRP: $739 AUD (Regular, -11°C bag)

Buy Now

I wish the red had stayed inside the bag, but apart from that it’s pretty good looking (and poofy)

Performance

Some might argue that the performance of a sleeping bag is how comfortable it is, but because comfort gets its own section in our review format, I’m going to focus specifically on warmth, weight, and waterproofing.

Any sleeping bag can be warm. Two kilos of insulation of any sort is going to keep you pretty toasty. But sleeping bags are always doing it with the smallest weight and size penalty they can manage and the One Planet Cocoon excels here.

At 932g, the Cocoon -11 is significantly lighter than the Mont Brindabella XT we reviewed, which is 1330g which was rated as low as -12°C for warm sleepers. Notably that bag is fully waterproof and built to withstand anything, but Mont also don’t use the standardised ISO 23537-1 testing system for their temperature ratings, so the temperature rating is harder to compare.

On the flip side, a Sea to Summit Spark -9°C is 730g, but it’s not as warm (ISO comparison is valid here), and it’s only water repellant all over, not waterproof. The Cocoon is also 4 degrees warmer than The North Face Blue Kazoo we reviewed, for only about 130g more weight, and $130 more cash.

So the Cocoon -11 strikes a middle balance here. The 10D Vapour Vent V2 used for the body of the bag is super lightweight and breathable, yet offers some water resistance and is impervious to down (I’m yet to see a feather). Meanwhile on the Storm Foot the fabric is Pertex Quantum Pro®, which is both warmer and properly waterproof.

The black waterproof ‘Storm Foot’ sets the Cocoon series apart

I love this because it’s the main part of the bag that gets wet when you push it up against the end of the tent or against the fly, and it’s also the part of me that’s always cold.

Oh and speaking of feathers, the down used is 800-850 loft, which is very premium and offers a great warmth to weight ratio You effectively won’t get down much superior to this and the compression into the provided 8L bag is impressive.

Feet have a weird way of regulating body temp in bed – just poking one foot outside the covers can cool me right down in summer – and the reverse is true with the Cocoon. My feet were always toasty, even with conditions around zero and my tent pinned open to maximise the cold. Granted, this isn’t -11°C (I think the worst I’ve seen is -7°C whilst camping on snow on the Main Range), but it’s pretty close to the -4°C degrees I use as a personal lower limit guide.

I slept with the doors pinned open to make it as cold as possible, you’re welcome

Comfort

So it’s warm, and it does so without being too heavy and bulky, nor too fragile and easy to get wet. It feels like there’s a Goldilocks philosophy being applied here – so does it apply to the rest of the bag’s attributes?

In a word: yes. The One Planet Cocoon lives up to its name with a very cosy hood that tucks around your face and shoulders. It’s more aggressively cosy than the One Planet Sonder with only a 59g weight penalty (but one extra degree of warmth).

There’s heaps of down in the hood, I had my first winter sleep without a beanie in years

The down is distributed with 55% on top, and 45% on the bottom, a bias designed to increase warmth on your non-mat side, and this extra loft is genuinely noticeable when you’re all tucked in.

Often mummy-shaped sleeping bags, while effective at saving weight, can be uncomfortable to roll around in or sleep on your side. The Cocoon counters this (and its name) somewhat with the box foot construction of the Storm Foot. This gives your feet a little more room when sleeping and because they’re not pushed into the sides of the bag, increases warmth.

But it’s most comfortable when you’re lying in your tent reading or talking. I’m a diehard side sleeper, but being able to relax my weary feet skyward without cracking open the bottom of the bag is a small luxury.

You can almost see the 55:45 down distribution from the side profile

Design

Despite its light weight, the appearance of the One Planet Cocoon doesn’t scream weight savings. There’s a burly YKK #5 locking zipper with an anti-snag slider (which works and should be mandatory on all bags), there’s a hefty draft tube behind the zipper too, and a chunky velcro cover that’s easy to use with gloves.

The zipper is tough and the draught tube has a tough fabric that ensures the zip never catches – it’s elite

The provided compression bag is also burly. Ultralight fiends will quickly swap it out for something lighter or waterproof, but so far I haven’t felt the need. Because One Planet fill their bags in Melbourne, they offer the chance to custom embroid your name on the bag, I thought this was a nice touch on something quite expensive that you plan to have for many years.

The zipper is full length, which is useful for ventilation and allows the bag to become a doona with a weird box foot if needed. The only thing I wasn’t a fan of was the drawstring to close the Cocoon around my head – it was just fiddly and sometimes got in the way when I was trying to sleep.

The zip cover is great but I think the drawstring needs something similar

The design definitely aids the warmth though. V baffles keep the down in the right as they limit down movement, which is a welcome change from some bags I’ve used where the down all migrates to one side and compresses. Over the chest, vertical baffles ensure down stays where it’s needed. Both design features can significantly increase warmth.

The box wall baffles also incorporate actual fabric on the sides of each baffle, rather than simpler stitched baffles that create pinchy cold spots where down coverage is effectively zero. The boxes aren’t square though, with less fabric on the inner layer of the bag to minimise loose fabric.

Big vertical baffles over the top half (including the back) give way to vertical V baffles that allow slightly more down movement

As you can see, One Planet has clearly thought a LOT about the design of the bag, so it’s no surprise that the size chart is very detailed with four different measurements. I’m 179cm and a pretty average build, so the regular size was fine for me, but if you need a bit of extra width One Planet sell an Expansion Gusset that zips in and adds 25cm to the shoulder width of the bag. Love it!

Sustainability

One Planet uses a non-PFC DWR treatment on the body fabric of the Cocoon. The down itself is also hydrophobic non-PFC treated, and ethically sourced according to International Down and Feather Laboratory standards.

But the big One Planet sell is local manufacturing. The company prides itself on engineering gear for local conditions, but there’s also significant control that can be exerted over the process when producing locally, as well as bulk shipping of raw materials or things like buckles.

The bags themselves are filled locally and made to order, ensuring control and minimal wastage, while other products are made entirely here or made overseas by long term suppliers.

It took a while to find on the website but One Planet offset the carbon impact of staff travel and deliveries, use locally-milled canvas, purchase renewable energy to run their operation and pull power from 120 solar panels on the factory roof. There are also clear standards on the factory page (though these could do with more specifics) and a focus on gear durability on repair.

We’re big fans of the ‘durability is sustainability’ approach, but it’s not enough on its own

One Planet’s motto is ‘Make it good. Make it work. Make it last.’ and it’s true that local producers are far more equipped to live this truthfully. If the gear was made 10,000km away, it’s almost always going to be cheaper to just send you a new one.

As a next step I’d love to see some more verified facts and figures on the site (such as how much bluesign fabric is used, rather than just a commitment to using it whenever possible) and more support for environmental initiatives.

It’s worth noting that One Planet is a strong supporter of outdoor education programs in Australia, offering hire and bulk supply of gear, which is important to train the next generation of people to get out there.

Price

The One Planet Cocoon is actually pretty well-priced. Granted, this will depend on if you have any idea of how much a sub-zero down sleeping bag costs, but safe to say you get more down for your dollar than a jacket.

At $739 for the model I tested it’s $210 cheaper than the Mont Brindabella XT I mentioned earlier, $60 cheaper than the Sea to Summit Spark, and $139 than The North Face Blue Kazoo. As discussed, all these bags have their pros and cons, but if we’re talking about the Goldlilocks zone then the Cocoon is kind of nailing it. 

It’s light enough, waterproof enough, and affordable enough, while still feeling and performing like any premium bag I’ve experienced. 

Final Thoughts

Reviewing a sleeping bag is tricky. The best indicator of how well it works is how long you remain unconscious for, and the range of confounding factors is vast.

But at the same time, it’s a simple binary. Was I warm and comfy? Absolutely. Does it tick all the other boxes for weight, and performance? I think my only criticism was a drawstring. Honestly, I’m incredibly impressed by the Cocoon series and One Planet’s approach in general. If you’re looking for your forever bag I’d make sure to check them out.

The main reason I’m hanging onto the provided compression sack, how good!