Walking Boots

AKU Superalp NBK GTX Boots | Review

A burly leather hiking boot with out-of-the-box comfort. Here's our verdict on the Aku Superalp Nubuck GTX

I’ve been using the AKU Superalp NBK GTX boots for the past few months on a mix of mountain paths and muddy forest tracks, and they’ve quickly become my go-to choice when I want some serious trail-proof protection. They aren’t lightweight hikers, but that’s exactly the point: they’re a rugged, dependable boot that can handle the weight of a heavy trekking backpack and keep you going when the terrain gets tough.

We actually reviewed the suede version of the Superalps way back in 2017, though they’ve made quite a few updates since then. The version we’ve reviewed here is the Nubuck option. It’s thicker, heavier, and warmer – more suited to hiking in the shoulder seasons and below the snow line in winter.

The Top Line

Purpose-built for backpacking, the Superalp Nubuck is a premium hiking boot made with top quality Italian materials. Of course, not everyone loves a burly boot. But if you do, I think you’ll get along very well with the Superalps.

Related: Best Walking Boots

While most hard-wearing, leather boots require some breaking in, I actually found these really comfortable straight out-of-the-box. You wouldn’t expect it from how rigid they look, but for me at least, they felt really cosy and supportive. I have it on good authority that this is due to AKU’s unique last shape that helps give their shoes an anatomical fit. Here’s a video that explains more about that:

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Pros: high quality materials, long-lasting, seriously protective, comfy
Cons: heavy, expensive

Buy the AKU Superalp NBK GTX boots: £320 at Aku.co.uk

What They’re Best Suited To

The Superalp NBK GTX boot is best suited to hillwalking and alpine trekking, particularly those doing multi-day stuff while carrying heavy packs, or traversing rugged terrain. In that respect, I’d say it’s particularly well-suited to four-season hillwalking and peak bagging – at least in conditions that don’t require crampons. It’s not, the best choice for light hikers or short-day walkers who prioritise minimal weight and flexibility. Check out our article on the best walking boots for women if you need more lightweight options in that respect.

Materials and Construction

The Italian Nubuck leather (2.6mm) is a big selling point for me. It’s durable, hard-wearing and has that classic hiker look too which I always love. This, in combination with the protective rubber rand, creates a really tough exterior.

The Superalp NBK boots are pictured here on test in the Lake District. All photos: Dave MacFarlane.

I’ve had issues with holes in synthetic boots in the past so have been very happy to really thrash these boots about on the trail and not feel too precious about it. And so far, you can barely notice the wear on these things.

Elsewhere, you’ll find a carbon fibre reinforced midsole and stiff lasting board for high shock absorption on the move. These reinforcements are also promising in terms of the longevity of the boot.

The Vibram fourà outsole has a reliable grip.

AKU's precise lacing system let you get a super refined fit.

I've found them very supportive around the ankles.

The IMS3-Exo sole

This is the first time I’ve come across Aku’s Internal Midsole System and I’ve been very impressed so far.

The IMS3-Exo sole technology works by integrating the brand’s Internal Midsole System (IMS) with a rigid external support structure (the exoskeleton). It basically combines multiple layers of cushioning that conform to the foot, with a lightweight yet rigid exoskeletal frame (medium-density PU rises at the back and sides of the boot) that controls torsion and enhances lateral support.

This dual-structure approach helps distribute pressure more evenly, absorbs impact during long days on the trail, and maintains a secure, precise fit even under heavy loads. The result? In my experience, you get a sole platform that keeps your feet stable and protected when walking on uneven or rocky ground, but still cushioned enough to reduce fatigue over long hikes. A little bit of everything really.

This combined with the grippy Vibram Fourà outsole creates one trustworthy boot. So far, it’s delivered excellently across a mixed bag of UK terrain, the only limit being properly greasy, wet rocks, an area where most footwear struggles.

Buy the AKU Superalp NBK GTX Boots: £320 at Aku.co.uk

Fit

I’m a UK size 6 (occasionally a 5.5) with pretty narrow feet, and straight away I found these very comfortable out-of-the-box. That’s quite a rare occurrence for a burly boot like this, and I was very surprised. I imagine that this means wider-footed folks might struggle or want to triple try before buying, though Aku do have a “Wide GTX” option in the suede version.

My only qualm is that the fit is a tiny bit wide-heeled for me. Granted, this issue disappears when I wear slightly thicker socks, but it’s worth bearing in mind if you have narrow heels like me.

Performance

One of the Superalp Nubuck GTX’s standout qualities, in my opinion, is its shock absorption and cushioning. Thanks to the dual-density PU midsole, it handles rough terrain really well and helps reduce foot fatigue on long walking days.

This translates to carrying a heavy backpack too. As a self-confessed heavy packer, I’ve found that the boot absorbs and handles the weight really well. While I’m yet to test these on a really long multi-day backpacking trip, I imagine that this will be a really useful quality in that regard. More updates to follow after my next backpacking trip then! If you want a boot that can stand up to heavy compression over long periods, PU midsoles are generally the way forward – they tend to have a better lifespan than soles with EVA.

As for the waterproofing, that’s done by good ol’ GORE-TEX. More specifically, it’s the “Performance Comfort” GTX which, in my experience, is reliably waterproof and also fairly breathable for a boot of this structure. Granted, it’s not the most aerated walking boot you’ll find out there (the suede Superalps probably offer more in that respect), but it’s also not the hottest either. I’d say it delivers a good balance between breathability and protection in this sense.

Verdict

All in all, I think the AKU Superalp NBK GTX boot is a top-tier hiking boot that balances protection, comfort, and long-term performance really well. Sure, it won’t be the boot I look for if I’m prioritising speed, but for what they are – solid, reliable, load-bearing boots – I think they’re a worth-while investment.

And an investment they are. While definitely not the cheapest boot on the market, I genuinely think you get what you pay for here – a very good boot that should last a good deal of a time.

Price: £320
Weight: 810g (per boot)
Best for: backpacking, thru-hiking, long-distance trekking

Buy the AKU Superalp NBK GTX Boots: £320 at Aku.co.uk