O’Neill Mutant Legend 4.5/3.5mm Wetsuit Review

O'Neill Mutant Legend 4.5/3.5mm Wetsuit Review

One of the most unique wetsuits ever made, the O’Neill Mutant has been a staple in our shop for over a decade. Now, O’Neill has re-released it with a new neoprene, a new thickness, and a new name; the Mutant Legend. Easily the most versatile suit we carry, the Mutant has a lot of cool features to it, and a few that aren’t immediately obvious. We’ve taken a closer look at the O’Neill Mutant Legend with a full review to see what makes this wetsuit so special. 


Starting with the name, the Mutant is called the Mutant because it can mutate between a chest zip and a hooded wetsuit. To our knowledge, it’s the only wetsuit in existence where you can detach the hood at the neck. This means the Mutant can be worn with a 2mm hood, a 2mm collar (like your average chest zip) or with neither.

Unique Modular Closure System
With zippers on the front and the back of the wetsuit, the Mutant at first glance isn’t your typical chest zip. This unique entry is what O’Neill calls a Modular Closure system. This design allows you to wear the different neck options and offers a huge range of versatility.

By unzipping the hood in the front and the back and swapping it out for the collar piece, you can wear the Mutant as if it were just a normal chest zip wetsuit. This feature makes the Mutant really versatile.

O'Neill Mutant Legend Chest Zip
The Mutant as a Chest Zip

For example, if you live on the East Coast, where the water temperature really fluctuates, it can be a pain owning a bunch of different-thickness wetsuits. With the Mutant Legend, as the water drops, you could add the collar for extra warmth and then eventually, a hood when it really starts to get cold. Between the different options, you can surf comfortably from the mid-60’s down into the 40’s, all in the same wetsuit. 

New Neoprene
Past versions of the Mutant were built with O’Neill’s UltraFlex neoprene which was their mid-grade rubber at the time. However, for 2020, the Mutant Legend has gotten a big upgrade and is without question the most flexible Mutant yet. This version is built with O’Neill’s best rubber, TechnoButter 3. With TechnoButter 3 in the body and TechnoButter 3X in the arms, the Mutant now has the same neoprene setup as O’Neill’s most flexible model, the Hyperfreak. 

On the inside of the Mutant, you’ll see that the chest and back panels have also been upgraded with Technobutter 3 Firewall. This red material better retains heat in the core better than most internal panels. The rest of the suit on the inside is lined with a TechnoButter 3x jersey. This jersey looks like corduroy and is the most flexible liner O’Neill produces. 

Mutant Legend Thickness

New Thickness
The Mutant was previously offered as a 5/4 or a 4/3mm, but the Mutant Legend now just splits the difference and is available as a 4/3+mm. The “+” means that O’Neill has skewed the cut on the thicker side, and it really is more of a 4.5/3.5mm than it is a 4/3mm. O’Neill in recent years has been building a few of their wetsuits in half thicknesses and 4.5mm seems to fit a good middle ground for a lot of coastlines.

Additional Benefits of the Modular Closure System
Aside from hood-swapping, the Mutant’s Modular closure system has some other cool unique benefits to it.

The first one is that you can re-order either the hood or collar. The neck on a chest zip suit is one of the areas that experience the most wear and over time can thin out. However, with the Mutant it’s no biggie, as you can order a replacement collar or hood.  You can also fit any size Mutant collar or hood on any sized Mutant. So if you have a larger than average head, for example, you could purchase an XL hood and use it with your size large Mutant. 

Another one of the lesser talked about benefits to this design is the flexibility. A traditional slant-zip chest entry has more rubber around the zipper, especially on the right shoulder. The Mutant’s neckpiece is streamlined and simply just pulls over your head. Without the excess material on the shoulders, the Mutant’s entry is slightly more flexible of an entry system than a slant zip. Even though there’s less material, it’s still warm, as the neck hole you enter through is tighter than a slant zip and there are cinch straps on either side to adjust the fit. 

O'Neill Mutant Legend Liner

Fit & Durability
The Mutant Legend fits true to size and wears really comfortable.  In the past, the Mutant was slightly harder to enter through the neck hole than your traditional chest zip. However, now that it’s built with Technobutter 3 rubber, it actually seems easier to get in and out than normal slant-zip chest entry wetsuits. 

Durability wise, the Mutant is one of those suits we almost never have issues with. In particular, the zippers seem to hold up really well, better than most wetsuits. Maybe it’s because the stress load is distributed to two zippers instead of all on one? Either way, the Mutant is built to last. 


Final Thoughts

The Mutant is a long time shop favorite and the new Mutant Legend is the best version we’ve seen, and one of O’Neill’s most flexible wetsuits. If you’re looking for an all-around great wetsuit than can cover a wide range of water temps, the Mutant Legend is our pick. 

If you have any questions on the Mutant Legend or any of the other suits that we carry, feel free to give us a call at 1-888-546-6176, leave a comment or shoot an email to us at support@cleanlinesurf.com

Shop the O'Neill Mutant Legend Wetsuit


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Established in 1980, with locations in Seaside and Cannon Beach, Cleanline Surf is the Northwest’s Original Surf Shop and remains your leader for surf, skate, and kitesurf needs.

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