Helly Hansen Odin 9 Worlds Infinity Shell Trousers review

Reviewed by GBAC member and ML Tom Holding.

The Odin 9 Worlds 3.0 Shell Trousers from Helly Hansen are the bottom layer to their corresponding hardshell jacket, which we already rate very highly. “Made for all-day movement on the mountain”, they’re said to deliver unbeatable performance and added comfort — all while coming with some extra features that improve your experience on big winter adventures.

Helly Hansen Odin 9 Worlds Infinity Shell Trousers

Ideal for: Winter mountaineering, mountaineering, summits, snowsports

Not suitable for: Trail running, fastpacking, UL activities, summer or mild weather

The Helly Hansen Odin 9 Worlds Infinity Shell Trousers are true 4-season overtrousers, packed with features that make them perfect for mountaineering activities. Fully water and windproof and designed for the most challenging environments, they come with Helly Hansen’s proprietary HELLY TECH membrane and the new LIFA INFINITY PRO coating, which means you stay protected from the elements without harming the environment.

Helly Hansen Odin 9 Worlds Infinity Shell Pants review

Helly Hansen’s Odin 9 Worlds 3.0 Shell Trousers are some of the brand’s most intentionally designed mountaineering hardshell trousers, created to keep you safe and comfortable on the most arduous winter mountaineering trips. They’ve been built to be worn all day and — have been produced iteratively thanks to feedback from Helly Hansen’s 55,000-strong pool of professional gear testers — they come with a series of extra features that are said to make them more comfortable and useful in the most serious winter environments.

Costing £400 when bought directly through Helly Hansen, this research and development doesn’t come cheap, however. They’re designed for serious mountain use and are therefore priced accordingly — but try not to be too put off by the lofty price tag. Despite being expensive, they’re still competitive with similar lines, such as the £380 Rab Latok Gore-Tex pants or the £450 Mountain Equipment Tupilak.

Designed to similarly high-specs as the Helly Hansen Odin 9 Worlds 3.0 Shell Jacket — the corresponding hardshell to these overtrousers — the pants promise added durability “for all-day movement on the mountainside”, delivering enhanced performance on all of your hiking, skiing, snowboarding or backcountry adventures through winter. But how do they perform in the real world?

Our experience using the Helly Hansen Odin 9 Worlds Infinity Shell Pants

The Odin 9 Worlds Infinity Shell Trousers from Helly Hansen are true mountaineering trousers designed to keep you safe on the harshest and most arduous adventures. So it’s only right to test them accordingly. To do so, I took them out on a series of mountaineering and hiking trips through the winter of 2023 and 2024, with them joining me on tests of the similarly impressive Helly Hansen Odin 9 Worlds 3.0 Shell Jacket — the accompanying jacket to these trousers that includes much of the same technology. All in, the trousers joined me on winter excursions through the mountains of Snowdonia, the Cairngorms, Glencoe and the Lake District — and I’m happy to say that I was able to put them up against some of the most challenging UK conditions imaginable. So, how did they do?

Fit

To start with, let’s take a look at the fit of the Odin 9 Worlds Infinity Shell Trousers, which have been designed with mountaineering in mind. This means they deliver durable and reliable coverage down the full length of your legs, come with a generously sized waistband so they fit over multiple layers, and feature large ankle cuffs to fit over winter boots. Having tested the trousers in Large, I even found that I could just about fit these over my snowboarding boots, though smaller sizes (or bigger boots!) might not allow this.

As these trousers are designed to be worn in serious winter conditions, the waist on the Odin 9 Worlds Infinity Shell Trousers is decidedly generous. This allows you to layer up and stay warm. The downside to this, however, is that if you’re only wearing baselayers or a singular fleece underneath, the waistline can feel too big. Thankfully, the trousers come with belt loops and fasteners so you can easily cinch everything tight, or you could even pair them with braces for added comfort.

Along the leg, the trousers are much slimmer and have more of a streamlined fit. For me, this meant that they fit snugly enough to prevent any material from flapping around in the wind or getting snagged on crampons, and the articulated panels over the knee offered enhanced mobility on challenging climbs.

Durability

When it comes to winter mountaineering shell trousers, you really want a layer that is ‘bombproof’: Something that can withstand crampon spikes, rocks ice and more, and do so with gusto without turning into ribbons. And in my experience, that’s exactly what the Odin 9 Worlds Infinity Shell Trousers do. Granted, this does mean that the material is comparably heavier than many other pairs of waterproof trousers, but that’s the cost for a layer that’s built to last — something that can reliably put up with the various demands of mountaineering.

One thing I really appreciated is the quality of the seams, which are completely clean when viewed from the outside. Inside, you see that they’re internally sewn and taped, which results in a flat, comfortable and long-lasting finish while also minimising the risk of water ingress over time. What’s more, durable reinforced patches have been added where it matters in order to add further protection against crampons, spikes and rocks.

Weather protection

When it comes to bombproof shell trousers, you don’t just want added protection from rocks and tools, but you want reliable protection from the elements, too. This is another area where the Odin 9 Worlds Infinity Shell Trousers excel. Made from a 3-layer, 100% polypropylene material, the trousers do an amazing job at keeping out wind-driven rain and constant snow, ensuring you have bone-dry legs underneath at the end of the day.

When it comes to breathability, however, this is often the first thing to be sacrificed in lieu of durability. And while these certainly aren’t as breathable as my summer trousers, they aren’t the worst I have ever worn. To combat this issue, long venting side zips add plenty of ventilation, (which I found myself using on long steep, uphill battles). These full-length two-way waterproof side zips also mean you can easily take the trousers on and off, even when you’re wearing crampons, which is a feature that I really appreciated when hiking on days when the weather kept changing.

Weight and Packability

The Helly Hansen Odin 9 Worlds Infinity Shell Trousers weigh in at 550 g, which is about average for hardshell trousers this durable and reliable. Some, like the ever-popular Mountain Equipment Tupilak pants are 10 grams heavier, whereas Rab’s equivalent offering, the Latok Gore-Tex pants come in 55 grams lighter. Honestly, however, you don’t feel the weight when you’re wearing them, so I wouldn’t worry too much about a few grams here or there when packing your bag for a deep winter mountaineering trip — the type these trousers were built for.

Regarding packability, these trousers do take up a bit of space, and I would recommend using a drybag to squeeze them down as much as possible. Again, don’t expect them to be as small as your summer pair. That’s why we carry bigger rucksacks in winter!

Additional features

As the Helly Hansen Odin 9 Worlds Infinity Shell Trousers were designed with intention, the trousers do come with a series of additional features that I particularly appreciated out on the mountain. Firstly, there is a generously sized pocket with an internal clip point. It has a large zip pull for easy use, and it never let me down once: Everything I stored in here stayed dry all day.

Much like the corresponding jacket, the Odin 9 Worlds Infinity Shell Trousers also come with a RECCO reflector. This is a passive device, sewn into the material, which makes it more likely that you will be found if avalanched. The technology works by reflecting radar signals back to a receiver. The technology does not degrade with age and if not mechanically damaged will last forever.

Helly Hansen Odin 9 Worlds Infinity Shell Trousers FAQs

Despite costing £400 when bought directly from Helly Hansen, we think the Odin 9 Worldfs Infinity Shell Trousers are worth the money. When you compared these overtrousers with other similarly high-quality mountaineering trouser hardshells out there, it’s clear that they’re competitively priced, and due to the durability, performance and eco-credentials of the pair, we think they’re a worthy investment if you can afford it.
Helly Hansen has not published any hydrostatic head ratings for the trousers, but in our experience, they’re plenty waterproof. We stayed perfectly dry underneath despite testing these in both torrential rain and snowstorm conditions.
For such a durable hardshell, the Helly Hansen Odin 9 Worlds Infinity Shell Trousers are surprisingly breathable. Naturally, they’re not as effective at mitigating moisture build-up as a lighter pair of summer overtrousers, but when paired with the long venting zips that run the full length of each leg, it’s easy to avoid getting overly clammy inside, we found that we could comfortably wear them all day.
The Helly Hansen Odin 9 Worlds Infinity Shell Trousers are very windproof. The thickness of the material prevents any and all wind from getting in.
The Helly Hansen Odin 9 Worlds Infinity Shell Trousers weigh 550 grams and can be quite large when packed down. If you vacuum seal them in a dry bag, however, they become much more portable and easy to carry — or you could just commit to taking a bigger bag through winter!

Conclusion

All in, I really rate the Helly Hansen Odin 9 Worlds Infinity Shell Trousers. They’re a fantastic pair of winter-weight overtrousers. They will protect you, are packed with features that make them suitable for winter mountaineering, and — although fairly pricey — are around the same as many of the competitors out there. And while they’re big, heavy and expensive, I feel like Helly Hansen has struck a great compromise on all three of these considerations: They are durable, portable, fit well, will protect you in arduous conditions, and — due to the durability — they should last you many seasons, thereby reducing the overall cost per wear and the environmental impact of the trousers. Which, to be honest, when it comes to hardshells like these, is about as much as you could ever possibly as for.

Helly Hansen Odin 9 Worlds Infinity Shell Trousers review

Helly Hansen Odin 9 Worlds Infinity Shell Trousers

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Helly Hansen Odin 9 Worlds Infinity Shell Pants review