Boreal have been steadily working through their range, updating each of the models in their collection. The Mutant is the latest to receive treatment. While it's had a fairly substantial overhaul, the focus of the shoe remains the same - top end performance bouldering. It's had an update to the rubber compound it uses, and now features Zenith Ultra 2.0, the brand's stickiest compound. What's the catch? Well, we do think the complicated fit won't be for everyone.

In Use

The Mutant 3.0 is designed for performance bouldering and sport climbing. From a UK perspective you can realistically narrow that down to bouldering, as the sport climbing we have here tends to be at the more vertical end of the spectrum,and the Mutant realistically performs at its best on the steep stuff (like you get in Spain, where the shoe is made). In light of that, and its softness, it would be extremely applicable indoors, although it's worth noting that the Mutant isn't a super-soft indoor specialist.

At the front end the Mutant sports between 4-4.5mm Zenith Ultra 2.0 rubber, which is Boreal's stickiest compound, and something we've been really impressed with previously. This is quite a lot of rubber compared to other brands, with the average these days being around 3.5mm. This extra rubber has both benefits and drawbacks. The benefits are that it offers more support on small edges, and it lasts a bit longer; the drawbacks are that it can, compared to more slender models, feel a little less sensitive. We've not had a huge issue with the shoe's sensitivity though, so maybe this isn't a big concern. There's plenty of rubber on top too, which is ideal for toe-hooking, scumming and smearing. 

Rob: The Mutant is great bouldering on both edgy and smooth rock types - so everything from limestone/rhyolite to gritstone/sandstone. When it comes to sport it'd ultimately be quite specialist, at least from a UK perspective, but if you're heading abroad to somewhere like Santa Linya (i.e. somewhere very steep) then it'd be ideal. 

Penny: I've primarily used the Mutant indoors. It's stiffer than your average indoor performance shoe, but the upshot of that is that it provides a bit more support, which is actually quite useful on edges. On smears, the rubber compound really comes into its own. As highlighted above, the fact that there's a bit more rubber underfoot means that they're likely to last a bit longer, which can sometimes be an issue whilst bouldering indoors, as you end up going through shoes quite quickly!!

Fit

Coming in both higher and lower volume versions, the Mutant 3.0 is definitely a specialist shoe as far as fit is concerned. It's fairly neutral in terms of width, but high in terms of volume - even the low volume version feels relatively spacious. Part of the reason for this is because the shoe is designed to be worn with your toes firmly knuckled up against the end, but even so it still feels quite roomy. To make matters more complex it has a relatively narrow opening, which makes it quite hard to fit your foot in. This leads to limitations in terms of fit, but is also annoying when you need to remove it, and put it back on, in between attempts.

When it comes to sizing we both went down 1 1/2 UK sizes, which felt about right, although both of us wondered whether going down 2 sizes would have yielded a better fit; however, we're not sure either of us would have managed to get our feet into them!

Rob: I've got quite a wide, high volume foot and found that I still had plenty of space above my toes. Ordinarily I would consider downsizing in such a scenario, but given how hard I found it to get the shoe on in the size I had I'm not sure that this would have been possible. Definitely one to try before you buy, if you can.

Penny: Like Rob, I've found the fit of the Mutant quite tricky. I've got quite a low volume foot, so had hoped that the low volume version would fit; however, even that has space above the toe. To make matters more complicated, I can only just get my foot into the shoe the size it is, so down sizing isn't a possibility. 

Summary

This is a good performance all-rounder for bouldering on a variety of rock types, and indoors. Whilst the Mutant has a lot going for it, the limiting factor in its suitability largely depends on whether or not it fits. That's the same for every shoe, but with the Mutant it matters more as a result of the relatively narrow opening, and because of the fact that both models are relatively high volume (and high volume feet aren't always the best at getting into narrow openings!).