Zone3 Aspire 2025 wetsuit review: cutting edge tech and an inspired use of sustainable materials make this a top choice for serious open water swimmers

It's incredible to me how far swim wetsuits have come in the 15 years I've been pulling them on and peeling them off. My first swim wetsuit was billed as a triathlon suit, but with 6mm thick neoprene all the way to the ankles, was an absolute battle to remove, even without the pressure of hopping on a bike after.

Fast forward to 2025 and it feels like, with its latest iteration of the Aspire, Zone3 has answered (almost) every complaint I've ever had about swim wetsuits.

And there's a lot to get excited about, so let's dive in:

Zone3 Aspire 2025 wetsuit: materials

Seeing manufacturers finally catch up with swimmers' desire not to pour themselves into petrochemical-based wetsuits has been one of the gratifying parts of my job in recent years.

With Finisterre championing the use of Yulex, and Zone3 switching to B-Prene for the new Aspire, it feels like the tide is turning (no pun intended). While suits using bio-sourced materials currently run on the costlier side, it's almost inevitable that over time these prices will come down, as they have with just about every other piece of wetsuit tech.

B-Prene is a limestone-sourced neoprene alternative, developed in Japan by Yamamoto. It's biodegradable in landfill, and tests have shown that under those conditions it should break down by approximately a third in just two years, continuing after that until it fully decomposes. That might leave you wondering how long it'll last you too. But incredibly, despite its ability to break down in landfill, B-Prene will remain intact during normal swimming conditions and home storage. By comparison, traditional neoprene isn't biodegradable, so 100 years after you've chucked your ragged suit away it'll still be hanging around and leaching nasty chemicals into wherever it ends up to boot.

What's interesting about limestone-based neoprene vs traditional oil-based neoprene is that it's also less absorbent, making it more waterproof. This doesn't mean you won't get wet using the Aspire. But it does mean the suit isn't going to suck up the water in the same way.

The use of a metal YKK back zip rather than a plastic one is a nice touch, and another nod to the quality of the suit. We're not cutting corners here.

Zone3 Aspire 2025 wetsuit: construction and fit

The Aspire 2025 is made from 25 individual panels, which has allowed Zone3 to target different thicknesses of B-Prene to enhance performance, and place different materials in key areas. Panels of different thickness are far from new in performance wetsuits, but the Aspire is incredibly detailed in this approach.

The upper chest and shoulders are 1.5mm thick (or thin) and cut from a single piece of B-Prene to allow for an impressive range of movement. The shoulder is a delicate joint that's easily compromised and many serious swimmers, myself included, find they suffer from niggles in this area. Keeping the B-Prene as thin as possible at this point makes a shoulder injury far less likely, even when tackling long distances.

The neck, lower arms, wrist cuffs, leg cuffs and crotch all use 2mm B-Prene - creating stretch where it's most needed. Elsewhere the torso uses 4mm B-Prene, injected with extra air bubbles to create a 'Body Rotation Enhancement Chest Panel'. Basically, it helps you rotate the right amount with your stroke, rather than over rotating. Zone3 calls this tech 'Aerodome', and the men's suit also includes Aerodome material on the legs, aiming to ease the problem cis male swimmers often have of sinking legs due to low body fat.

The waist, hips and legs use thicker panels between 3mm and 5mm, creating extra buoyancy where it's most needed to keep you aligned correctly in the water.

One of my favorite features of this suit is the 'catch' panel on each sleeve. Zone3 don't list what this is made of, but it feels like some kind of nylon/spandex and helpfully creates cool spots to improve your proprioception in the water.

As this is a high performance suit, it is on the tight side, which can take a bit of getting used to. But all this slim cut panelling means this suit really pulls you in, theoretically allowing you to move faster through the water. Despite the snug fit I've found it to be comfortable to wear, with no chafing so far around the armpits and neck edging, although the longest distance I've swum in it so far is only 2.5 miles (4km).

So, how does it perform in practice?

Zone3 Aspire 2025 wetsuit: performance

Tthe Aspire 2025 is a fast suit, whatever your discipline. Normally it takes me about 2km before I start to hit the 'flow' zone so loved by distance swimmers, when everything clicks into place and you're just gliding through the water without having to think too hard about technique.

So when I first put this suit on I thought I was just having a good training day as that flow feeling kicked in much sooner. But after repeated use I've come to realise it's the suit that's helping me hit that zone quicker.

This is due to a combination of factors. Firstly, all that fine tuning of the panelling matters. The bits that need to float the most float the most. The bits that need to stretch the most stretch the most. And the way the suit pulls you in and compresses you means there's physically less of you to cut through the water in the first place. The addition of the catch panels means you can feel where your arms are in the water far better than in standard neoprene, which allows you to get the most out of your stroke.

Zone3 have also looked at drag reduction, using a Super Composite Skin nano-coating to cut it to just 0.021 (normal neoprene has a drag co-efficient of 4.0).

All this tech combines to create a whizzy feeling in open water, so be prepared to feel the difference - you're not imagining it.

Zone3 Aspire 2025 wetsuit: warmth

When assessing high performance swim wetsuits, warmth isn't my first consideration – after more than a decade swimming long-distance open water, I'm pretty hardened to the cold.

But for super lean triathletes, or anyone else who hasn't got years in open water under their belt, fighting the cold is a serious concern, as in water below about 60-70°F (15-21°C) most people will become hypothermic, even if that's after multiple hours. Due to the thinness of the neoprene in a lot of the panelling, I think it's a stretch to call the Aspire a winter suit. But most big swim events and triathlons run from mid-summer to early autumn, and it should be sufficient for that, unless you have very low body fat.

If that is the case, I'd recommend buying a size larger and getting a neoprene vest to wear underneath it, to add extra protection to your core. Handily, Zone3 make one, and, having had my neo vest for at least eight years, I can testify that it's absolutely a worthwhile investment. I wear it under my wetsuit for swims of two hours or more, and under a long sleeve swimsuit for winter swims, when I can't be bothered to put on a wetsuit for a 10 minute dip.

Zone3 Aspire 2025 wetsuit: getting changed 

If you've ever battled to remove your wetsuit after a long swim, I have one big tip for you: take it off in the water. It is a night and day experience and, as long as the suit isn't too tight around your ankles, in the water it should simply slide off.

However, triathletes don't have the luxury of doing this, and Zone3 have done something about it. The suit's Silk X lining is soft against the skin and makes it easier to slide in and out of it and the Pro Speed Cuffs at wrist and ankle are designed to be extra stretchy. No complaints here.

Sizing

Before I wrap up I do need to have a moan, but it's not specifically aimed at Zone3. When are brands going to start making bigger wetsuits for serious swimmers? If you've ever taken part in an open water event you'll know first hand that swimmers come in all shapes and sizes and a lot of competitors at amateur level are on the larger side.

I may be tall for a cis woman, but as a UK 16 (US 12) I'm the national average clothing size. And yet, when I stacked up my measurements, I had to choose the largest women's size available in the Aspire 2025. It fits me well, but this kind of sizing restriction is exclusionary. What's doubly frustrating is that, across the range for both men's and women's sizing are several 'inbetween' sizes if you're a Small or a Medium.

I haven't reduced the score of this wetsuit because the fit really was exceptional, and it's an industry-wide issue, rather than something specific to Zone3. But brands do need to catch up. One visit to the start line for the Dart 10k (in any category) will show you that slimness and swim ability are not directly related - please think bigger!

So, given that I've awarded it a 100% score, you may be asking whether the Aspire 2025 truly is a 'perfect' suit, given my moans about sizing.

Yes, there are commercially-made suits that are faster (the Zone3 Limited Edition VanquishX is worth a look if money is no object), yes there are cheaper suits that offer similar performance, and yes I wish the sizing was more inclusive.

But it's the combination of sustainable materials with the performance it offers, that warrants the new Aspire 2025's perfect score and leaves me feeling I can recommend this wetsuit to serious open water swimmers without any hesitation. As long as you can get one to fit you...

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