Wild CampingHelly HansenWaterproof Shell Trousers

Helly Hansen Odin 9 Worlds Infinity shell trousers review: reliable protection built for all-day mountain movement

Reviewed by Tom Holding — mountain leader, Mountain Training Association member and owner of TH Outdoor Adventures.

The companion trousers to the Odin 9 Worlds jacket we already rate very highly — designed for the most challenging mountain environments and tested accordingly.

✓  Top PickHelly Hansen Odin 9 Worlds Infinity Shell Trousers Weight550 gMembraneLifa Infinity ProPrice£400 The good✓  Tough, durable 3-layer material
✓  PFAS-free Lifa Infinity Pro membrane
✓  External thigh pocket (waterproof)
✓  Full-length two-way side venting zips
✓  2-way crotch zip for harness use
✓  Large ankle cuffs — fit over winter boots
✓  Articulated knee panels
✓  RECCO reflector
The not-so-good✗  A little heavy at 550 g
✗  Waist sizing generous — may need cinching over fewer layers
Check price at Helly Hansen →

At a glance

Overview

The Helly Hansen Odin 9 Worlds Infinity Shell Trousers are the companion leg layer to the Odin 9 Worlds 3.0 Shell Jacket — a jacket we already rate very highly. Built for the most arduous winter mountaineering trips, they have been produced iteratively through feedback from Helly Hansen’s 55,000-strong pool of professional testers, and come with a series of extra features designed to improve comfort and usability in the most serious winter environments.

At £400 direct from Helly Hansen, this research and development does not come cheap — but they remain competitive with the Rab Latok GORE-TEX trousers (£380) and the Mountain Equipment Tupilak (£450). And thanks to the PFAS-free Lifa Infinity Pro membrane, you are getting serious mountain performance without the harmful chemicals.

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How we tested

These are true mountaineering trousers, and we tested them accordingly. Tom took them on a series of mountaineering and hiking trips through the winter of 2023 and 2024, alongside the corresponding Odin 9 Worlds 3.0 Shell Jacket. In total, the trousers saw winter excursions through the mountains of Eryri (Snowdonia), the Cairngorms, Glencoe and the Lake District — put up against some of the most challenging UK conditions imaginable.

Features and performance

Fit

These trousers have been designed with mountaineering in mind: durable coverage down the full length of your legs, a generously sized waistband to fit over multiple layers, and large ankle cuffs to accommodate winter boots. Testing a Large, it was just about possible to fit them over snowboarding boots — though smaller sizes or larger boots might not allow this. The generous waist is deliberate — it lets you layer up and stay warm. The downside: if you are only wearing a baselayer underneath, it can feel too large. Belt loops and fasteners let you cinch everything tight, or pair with braces for extra comfort. Along the leg, the trousers are slimmer and more streamlined — snug enough to prevent flapping in the wind or snagging on crampons, with articulated knee panels for enhanced mobility on technical climbs.

Durability

For winter mountaineering shell trousers, you want a layer that is bombproof — something that can withstand crampon spikes, rocks, ice and more, and do so with gusto. In our experience, that is exactly what the Odin 9 Worlds Infinity Shell Trousers do. The material is comparably heavier than many other waterproof trousers, but that is the cost for a layer built to last. The seams are completely clean viewed from outside, internally sewn and taped for a flat, comfortable finish that also minimises water ingress over time. Durable reinforced patches have been added where it matters — protection against crampons, spikes and rocks.

Weather protection and breathability

Made from a 3-layer, 100% polypropylene material, the trousers do an excellent job of keeping out wind-driven rain and constant snow — bone-dry legs at the end of the day, every time. Breathability is often the first thing sacrificed in lieu of durability at this class, and while these are not as breathable as summer trousers, they are far from the worst. Long venting side zips add plenty of ventilation for long steep ascents. These full-length two-way waterproof side zips also mean you can easily take the trousers on and off even when wearing crampons — a feature Tom appreciated enormously on days when the weather kept changing.

Additional features

The generously sized thigh pocket has a large zip pull for easy use and kept everything stored inside bone dry throughout testing. Like the corresponding jacket, the trousers also include a RECCO reflector — a passive device sewn into the material that reflects radar signals back to a receiver, making it more likely you will be found if avalanched. The technology does not degrade with age. And the 2-way crotch zip provides genuine harness compatibility for technical climbing days.

“Helly Hansen has struck a great compromise: durable, portable, well-fitted, and protective in arduous conditions. And due to that durability, they should last many seasons.”

Our verdictA fantastic pair of winter-weight overtrousers — packed with features that make them perfect for mountaineering.Tom really rates the Helly Hansen Odin 9 Worlds Infinity Shell Trousers. They will protect you, are packed with features that make them suitable for winter mountaineering, and — although fairly pricey — are competitive with equivalents from Rab and Mountain Equipment. While they are big and heavy, Helly Hansen has struck a great compromise on all three considerations: durable, portable, well-fitted and protective in arduous conditions. And due to that durability, they should last you many seasons, reducing the cost per wear and environmental impact over time. Which, for hardshells like these, is about as much as you could ever ask for.Buy the Helly Hansen Odin 9 Worlds Infinity Shell Trousers →

FAQs

Are the Helly Hansen Odin 9 Worlds Infinity Shell Trousers worth the money?Yes. At £400 direct, they are competitive with the Rab Latok (£380) and Mountain Equipment Tupilak (£450). The durability, performance and eco-credentials make them a worthy long-term investment.

How waterproof are the Helly Hansen Odin 9 Worlds Infinity Shell Trousers?Very waterproof. Helly Hansen has not published hydrostatic head ratings, but in testing through torrential rain and snowstorm conditions, the wearer stayed completely dry underneath.

How breathable are the Helly Hansen Odin 9 Worlds Infinity Shell Trousers?Surprisingly breathable for such a durable hardshell. Not as effective as lighter summer overtrousers, but the full-length venting side zips make it easy to manage moisture build-up and wear them comfortably all day.

How windproof are the Helly Hansen Odin 9 Worlds Infinity Shell Trousers?Very windproof. The thickness of the 3-layer polypropylene material prevents wind penetration entirely.