The 2025 K2 Anthem BOA 125 W Is Among The Stiffest Women's Ski Boots

• Size skied: 24.5
• Sizes available: 22.5 - 27.5
• Stated Weight: 1,658g @ 24.5
• Stated Flex: 125
• Binding Compatibility: Alpine with Toe-Only Tech Fitting
• Forward Lean: 12 (14 with wedge)
• Stated last width: 97 - 100mm

Fit:

The K2 Anthem BOA 125W impressed me with its quick-to-customize out-of-the-box fit. The toe box offers a balanced feel—ample vertical room, narrow width, and standard length. There is an adjustable 97-100mm stated last, managed via the BOA® Fit System, which in my experience delivers a fit in the middle of its claimed range.

The heel pocket has medium volume, and an accommodating instep— plenty of room for my high instep, however, my low-volume heel is itching for a bit more support. There is a built-in canting adjustment in the calf pivots, which I loosened one notch. Getting in and out of the boots is smooth, and while the BOA-equipped Intuition power wrap liner was a bit sticky at first, it’s loosening up with use, making removal even more seamless over time.

Features:

The Anthem BOA 125W incorporates innovative BOA technology on both the shell and liner and several small customizable adjustments to help you as a skier optimize your fit.

Starting with its most notable and standout BOA H+i1 Fit System. Replacing the traditional setup of two lower buckles across the top of the foot, this system uses a micro-adjustable dial with a burly 3mm BOA cable. The BOA does a good job of evenly distributing pressure across the foot, but doesn’t eliminate pressure points. The micro-adjustable dial also works in reverse, allowing you to loosen up the cables for chairlift rides or after skiing a more demanding line without completely releasing all of the tension.

The shell is constructed of K2’s Powerlite Pebax plastic, which utilizes shell walls of varying thicknesses and four different types of TPU, and is designed to be responsive in variable conditions and relatively lightweight. To add stiffness, it features K2’s Power Plate, Powerfuse Spyne, and a Power Strap. The Power Plate is an adjustable piece of hard plastic that sits between the buckles and the liner above your shin and raises the height of the front of the cuff in 10mm increments to increase stiffness. On the rear end of the shell sits what K2 calls its Powerfuse Spyne, a rigid Y-shaped support that stiffens the boot laterally.

Inside is a fully heat-moldable Intuition Power Fit Wrap BOA Liner. Similar to the classic Power Wrap, this line has a small BOA on the outside to cinch the liner around your leg, creating a secure fit that caters to downhill performance.

The boot also includes adjustable rear cuff support that can be easily customized to fit different calf shapes. Historically, I haven’t had issues with calf tightness in boots but I loosened this after my first few days out and this has improved the fit.

Equipped with a GripWalk sole and toe-only tech fittings, this boot is compatible with most alpine bindings on the market. It can also be utilized with touring setups such as the Shift, Marker Duke PT 16, and CAST Freetour Kit, which all use a tech toe for uphill touring, but function as an alpine binding while skiing.

Uphill Performance:

Putting this boot into the ‘hybrid/crossover’ boot category feels like a stretch, and its use cases for uphill touring are quite niche. As I briefly mentioned, the touring bindings that the Anthem 125W BOA is compatible with are limited to those that use tech fittings for the uphill only and convert to an alpine-equivalent binding for the descent.

The boot has no walk mode, and while it’s not as heavy as other alpine boots out there, it’s rigid and not high on my list of boots that I would like to go on a walk in.

That being said, of all the places in the world you might need a boot like this, here in the Tetons is probably top of the list of where this boot will get uphill use. It's ideal for lift-accessed side country adventures with short tours, or for tackling high-consequence lines where downhill performance takes priority over the uphill journey. It's also a great option for traveling skiers who will be doing the majority of their skiing at a resort, but need a boot capable of the occasional tour.

Downhill Performance:

Downhill performance is where this boot shines. True to its stated flex, it’s the stiffest women’s boot I’ve ridden, having tried a plethora of 115 flex boots from almost every brand out there. I wouldn’t put it up against an aggressive race boot, but it offers a refreshing new option for a freeride-specific women’s shell for those looking for something stiffer.

The Anthem 125 is powerful, and I’m feeling confident in its performance in both ideal and variable conditions. Out of the box, the stiffness felt rigid with little feedback or dampness in the shell, yet this lent itself to keeping my heel stable and locked in without having to crank down too hard. I have narrow feet and a tall instep, so often I struggle with my heel swimming in the boot, yet tightening it down much more for security causes painful pressure points on the tops of my feet.

As I’ve continued to get more days on it, the shell has softened a little bit and is more responsive, but I’m having to crank down on the BOA and buckles more to get the same performance and keep my heel locked in. So far, the BOA has not eliminated the pressure points on the top of my foot, but they are less intense than my experience with buckles. There are little lines along the shell where you tighten down on the BOA as ‘placeholders’ to help you note how far you’re tightening down (much like knowing which notch on your buckles is your go-to).

We’ve probably all experienced being in between buckles on your boots where the buckle you’re on isn’t tight enough, yet the next one is too tight. The ability to make micro-adjustments is perhaps my favorite part of the BOA Fit System. While the cranking can be a bit tedious at the beginning of the day, once I find my spot, loosening or tightening before and after a run goes quickly.

Overall, this boot continues to be the stiffest and highest-performing women’s freeride boots that I’ve found.

What does the K2 Anthem BOA 125 W's ideal skier look like?

The K2 Anthem 125W is a great boot for an aggressive freeride skier looking for a hard-charging women's alpine boot that provides the option for the occasional short tour or side country mission.