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Review: Ultimate Direction AK Mountain Vest 3.0

After a couple of years of trail running with my trusty Ultimate Direction Wasp I decided it was time to retire it and move on. When I purchased the Wasp I was transitioning from primarily hiking to running and was seeking something that fit more like a backpack and less like a vest. Since then, I’ve been running a lot more and have come to appreciate the form factor of the vest pack. I initially purchased a relatively inexpensive Mountain Hardwear race vest for local runs and supported routes. However, it didn’t have enough capacity for big days in the mountains. I needed something with more capacity!

Ultimate Direction AK Mountain Vest 3.0

Ultimate Direction AK Mountain Vest 3.0

The AK Mountain Vest 3.0 is part of Ultimate Directions “Signature Series”. the Signature Series products are designed with the assistance of famous ultra runners. The AK Mountain Vest was no exception. Anton Krupicka, a well known and accomplished ultra runner was the mind behind this design. Previously, Anton Krupicka was the signature athelete behind the “AK Race Vest” which is an entirely different minimalist vest. The AK Mountain Vest 3.0 follows Anton’s general shift in priorities towards big unsupported mountain runs on technical terrain. Heck, they even threw an ice axe loop on the back!


  • Two Ultimate Direction 500ml “Body Bottles” included
  • Sliding rail sternum straps
  • Bottle holsters tighten to carry phone or camera
  • iPhone compatible pocket
  • Unique, on-the-go trekking pole holders
  • Double ice axe loops
  • Soft and flexible 150g mono-mesh
  • External stretch pocket for organization
  • Secure lateral pockets


  • Volume Capacity: 702 in3 / 11.5L
  • Weight: 11.55 oz. (14 oz. with bottles) / 330 g (400 g with bottles)
  • Height: 15.7 in. / 40 cm
  • Width: 11.4 in. / 29 cm
  • Depth: 7.5 in. / 19 cm


  • 150g Knit Mono Mesh: New 150gsm harness conforms to your body for absolute comfort and superior load carrying
  • 180g Darlington Power Mesh: Lightweight strength with differential stretch in the x and y axis for enhanced load management
  • SilNylon/66: Silicone-Impregnated 30D nylon with a polyurethane face creates a permanently waterproof fabric, and substantially increases seam and tear strength

Sizing and Fit

Cinching up the sternum straps with a full load.

I had issues with the sizing of this vest. I’m 5’7 and about 145 pounds. Using Ultimate Directions instructions they tell you to measure at the base of your ribs. My “rib base” measurement was about 32″ in circumference  which unfortunately lands me right in the middle of sizing. I was on the high side of the small, and on the low side of the medium.

Sizing at bottom ribs (Taken from Ultimate Directions Documentation):
  • SM: 24 – 33 in. / 61 – 84 cm
  • MD: 31 – 40 in. / 79 – 102 cm
  • LG: 36 – 46 in. / 91 – 117 cm

I ordered a small, which was a huge mistake. I could barely get the vest over my shoulders to put my arms through it. I’m not a big guy by any stretch of the imagination. This vest seemed like it was designed for a child… very odd. I contacted UD and had the vest replaced with a Medium. This fit better, but actually seemed too big?! With the vest empty I had to cinch down all of the webbing straps to get the vest to stay close to my body and not flop around. I decided to settle with this inconvenience and keep the medium since the pack was secure enough once I put a few items in it. There’s pretty much no circumstance that would have me wearing this pack completely empty anyways.

Sizing Adjustment

To alleviate the issues with the sizing as previously mentioned there are an ample amount of adjustments that can be made to the vest. Across the front there are two adjustable sternum straps that also slide vertically to allow you to tailor the fit. Under the arms are two “lat straps” that tighten the base of the vest closer to your rib case. These straps helped tremendously when I was wrestling with the sizing of this vest.

Storage Capacity

Packing Up!

Here’s where this pack shines. Ultimate Direction markets this vest with an 11.5L capacity. When I first started filling this vest I thought it might be too small. However, it turned out that it was even bigger than I needed! Aside from the large volume main rear compartment this pack is peppered with pockets. Very little exterior space goes unused. Up front I was able to hold two 500ml bottles, Katadyn BeFree filter and bottle, My Samsung Galaxy S8, lots of gels and snacks, pills, and other quick access items. In the back I had a spare jacket, 1.5L hydration reservoir, SPOT Gen 3 messenger, Black Diamond Z trekking poles, my car keys, and my first aid kit… Pretty impressive! What’s also cool about the main compartment is that the outer shock cord can be looped through inner hooks that reduce the volume of the pack. This is great if you’re planning on using the vest on a day that may not require carrying a bunch of stuff and you don’t want your hydration reservoir sloshing around.

Large rear compartment features a full top to bottom zipper.


SPOT Gen 3 in exterior pocket

Up Front:

  • Two draw string closure bottle pockets
  • Two medium sized lower stretchy bottle pockets
  • One large lower rib pocket (Left)
  • One “cell phone compatible” lower zipped pocket (right)
  • Two velcro closure pill pockets

Lat Pockets can hold a lot of easy access stuff.

In Back/Sides:

  • One large main compartment
  • Large Outer stretchy power mesh pocket with Shock Cord
  • Hydration reservoir sleeve with securing strap
  • Two small outer zipped pockets (one with key fob)
  • Two under-arm lat pockets (these are huge!)

Hydration Compatible Sleeve

What I Like

First big 30+ mile run with the AK Mountain Vest 3.0

I never have to take it off! My first big run with this pack was a 30 mile Pemi Loop. 9+ hours of unsupported wilderness travel was a perfect test for this vest. During the entire time I never had to remove the pack to get to something I needed. The only time I’d need to remove the pack would be for first aid, or to change layers. I filtered my water through my “quick fill kit” with my Katadyn BeFree directly into the hydration reservoir in the vest without removing it.

Huge Lat Pockets! – The side “lat pockets” were perfect for stuffing all kinds of food in. I had Stinger Waffles, Granola, Energy Gel’s, and Gummy’s loaded in those pockets and they were super easy to unzip and get to without having to be a gymnast.

Front Vest Storage – The “cell phone” pocket was large enough for my Samsung Galaxy S8 however, I didn’t keep my phone in there as I felt it kind of digging into my ribs. I ended up keeping my phone in the stretchy pocket that was in front of the water bottle. Throughout my entire day I never found the pack to be chaffing or uncomfortable. I actively adjusted the sternum straps as I drank water to reduced the volume and keep things snug. I used the smaller exterior main pocket to carry my ID, and for my SPOT Gen 3 messenger. The top pocket worked great for my SPOT Messenger as I was “live tracking” and its a good position to face the sky for a solid GPS fix! Up front, I also had my water filter in the lower stretchy pocket so I could scoop up and filter water without having to stop very long.

Looks – With the blue/black/gray theme this is an attractive looking vest! I really appreciate good looking gear even if it’s not the most important feature. Because who doesn’t want to look good in pictures?

What I Don’t Like

This vest is great, however there are a couple of things that could be better.

The Fit! This is a big one. I feel like a lot of runners will struggle to find the right size if they’re in the Small/Medium territory with this vest. The two sizes are so different they might as well be entirely separate products. One being designed for smaller women and kids? I’m fairly happy with my size medium as long as I have contents stuffed all over it. However, My sternum straps are pretty much as tight as they’ll go which means if I lose any weight I may be out of luck.

The Mesh Inner Back  This isn’t a huge deal, but the inner back material is made of a course mesh. This means when you sweat it will go right through the mesh and be absorbed by anything in the main compartment like spare layers or socks. The Silnylon material on the exterior of the pack is waterproof which is great for a little rain or mist. However, this acts as a vapor barrier for anything trying to dry out inside the pack.

Pill Pockets – These are a handy feature located at the top of the vest shoulders. Designed to carry salt tabs, a gel, or good ole ibuprofen. One of these pockets is stretchy, one is a silnylon waterproof type. They are functional but they are shaped funny. The opening is actually narrower than the base of the pocket. When I was trying to quickly pull a tiny pill out of the pocket while running I found myself digging around with my finger. Removing pills are a little tricky unless they’re in a plastic baggy or something.

Hydration Reservoir Sloshing – I used a Solomon 1.5L Hydrapak Reservoir with this vest. I found that once I drank 50% of the water the reservoir would slosh side to side a bit despite how tightly I had adjusted the vest. It wasn’t a huge deal but a minor annoyance. This could be an issue with my particular reservoir as it’s pretty narrow and the vests rear pocket is very wide.

How the fully loaded vest rides on my torso.


If this vest fits your body its hard to beat! The AK Mountain Vest 3.0 is Light weight, large volume, tons of pockets, comfortable, and attractive looking. This is a winning combination from a great company. Ultimate Direction has refined their manufacturing and design to offer up a killer vest for super long, rugged runs in the mountains. Just make sure it fits first!

Buy your AK Mountain Vest HERE and help support this site!

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