From Alpine Ice to Deep Canyons: A Field-Tested Review
Summer pulls many of us outdoors, but a lucky few venture far beyond the marked tracks, into places that still feel truly untouched. Landscapes thick with emerald moss, heavy mist, and cavernous cliffs that swallow the sun. That's where you'll usually find me - alongside a rotating cast of canyoners, climbers, hikers, and alpinists chasing discomfort for fun.
Over the past few months, I made it my mission to properly stress-test Untouched World's Mountainsilk™ Half Zip. Not in curated conditions, but in environments that demand everything from your gear. Whether this fabric was pushed beyond its limits, or finally used exactly as intended… well, that's what this review is for.
This is an honest account, dirt, sweat, flaws and all, from someone who relies on their layers to perform when it matters.
A Quick Run-Down: Why Merino Matters
If you spend time outdoors, merino probably isn't new to you - but it's worth revisiting why natural fibres remain the go-to for serious adventurers. I'll be rating this top based on the following benefits:
Wool excels at temperature regulation, thanks to its ability to trap warmth when it's cold and release heat when you're working hard. That means your body expends less energy trying to self-regulate - critical in alpine or high-output conditions.
Then there's moisture management. Merino can absorb up to 33% of its own weight in moisture vapour without feeling wet. This prevents the dreaded “after-chill” you get when stopping in cold environments after heavy exertion - a common and dangerous issue with synthetics.
And finally: odour resistance. A lot of us outdoor enthusiasts will be ashamed to admit it, but when you're spending multiple days out in the mountains, you want to pack essential layers only. We can often spend a few days wearing the same clothes to cut down on weight. Smell is all part of the experience.
Untouched World describes the Mountainsilk™ Half Zip simply:
“In nature, or on the treadmill of life, this top will keep up with you, no sweat. Literally.”
With 25 five-star reviews backing the claim, it felt only fair to test it properly.
The Adventures
Mount Aspiring
The first trial was a three-day alpine mission up Mount Aspiring.
Day one involved mountain biking into Aspiring Hut, securing the bikes from kea, then continuing 15km on foot toward Collin Todd Hut - perched at 1,800m and accessible only by helicopter or a full alpine approach: steep terrain, glacier travel, and ice climbing.
We reached the Bonar Glacier at sunset, roped up, crossed the final kilometre over hidden crevasses, then climbed the last 100 metres with crampons and ice axes towards the hut. Thirteen hours of moving time, with the slightest mistake potentially fatal, all while carrying a 30kg alpine pack, is anxious work.
For the entire day, I wore:
- Mountainsilk™ Half Zip
- Lorna Jay leggings
- A lightweight wind blocker
That's it.
Sweaty doesn't begin to cover it. Imagine a thousand burpees with a small person strapped to your back.
And yet… the fabric performed.
Once we hit the snow line, all I needed was an outer shell. The same top came straight back on for our 14 hour summit push the next day, and again for the 12-hour exit.
Performance ratings (Alpine use):
Temperature regulation: 9/10
Slightly warm during intense ice climbing but easily managed by venting the zip.
Moisture management: 9/10
Impressively dry against the skin - no cold shock when stopping.
Odour resistance: 7.5/10
Let's be realistic. This was extreme. Only the underarms held any smell - my synthetics didn't survive the car ride home - neatly bagged up and away from vulnerable nostrils.
Wear & tear: 10/10
Not a single scratch of pull was found of this top – despite it taking on sharp rocks, equipment, and muddy ridges.
Canyoning: Nelson & Haast
After a quick cold wash, the Mountainsilk™ went straight back into action - this time for four days of back-to-back canyoning across Nelson and Haast.
Canyoning means long approaches in the middle of Timbuktu, humidity, rope work, crawling, scraping, and constant abrasion. It's not kind to clothing. The sport has many risks, including flash floods, deep and dangerous water currents, falls from extreme heights… the list goes on.
In a remote dry canyon near Mount Owen, scrambling through moss-covered rock bowls and muddy descents, a gang of 5 adventurers made their descent. From crawling on your belly and arms, to working hard on the ropes, everything you wear starts picking up moss, soft soil, and sweat.
Everything except… the Mountainsilk™.
Despite five hours of heavy work, it remained almost completely clean - and dry. Bizarre, but impressive. I'm still not sure how that happened, and I'm not sure I could duplicate those results.
We're four days in now, our final canyon complete, and nothing left to do but go for a celebratory cocktail. We gather round for the most important safety test of the day… the sniff test. Despite not having a wash after four days, multiple canyon approaches, and zero washes, it passed the “do I smell” assessment. Not pristine — but restaurant-acceptable. (And yes, I tested this.)
Performance ratings (Canyoning / approach):
Temperature regulation: 8/10
My biggest regret was wearing this while scaling 400m up during an extremely humid day, purely a mistake of my own. I wouldn't recommend this during exertion if you're in humid hot weather. But I wouldn't recommend wearing anything under those circumstances.
Moisture management: 11/10
This blew my mind for moisture management. I never felt the classic “wet chill” after any of our activities.
Odour resistance: 9/10
Shockingly good given the conditions. I successfully snuck into a Wanaka restaurant for a celebration cocktail, looking sleek and tidy, without a single judging glance.
Wear & tear: 8/10
Minor pilling from a mesh-lined shell - avoid textured linings if you want it pristine.
Final Verdict
Without a shred of bias, I can say the Mountainsilk™ Half Zip has become a genuine adventure staple for me.
What surprised me most wasn't just how well it performed; it was how much I looked forward to wearing it. After long, hard days in the mountains, I'd reach for it instinctively. And I'll admit it, every time I zipped that beautiful little kite zip up to my chin, I felt quietly proud to be wearing it. Maybe some of you know that feeling too?
The fit is flattering, the fabric feels lush, and its performance outpaces every other thermal I own. It's rare to step straight from alpine terrain into town feeling warm, presentable, and – importantly - like a normal-smelling human.
For me, that's the magic. Technical excellence without sacrifice. Comfort without compromise. A piece that works as hard as you do, and still carries you into untouched places without feeling like an imposter. Overall rating: 9.5/10
