Review: Ultimate Direction AK Mountain Hydration Vest 3.0


Basic description: The third generation of this hydration pack inspired by and designed with Anton Krupicka is lighter than the previous generation and provides more carrying capacity. The pack is compatible with rear fluid reservoirs (not included), but is functionally more efficient when using the dual soft flasks in the front pocket. This vest runs large, so consider downsizing from the measurements listed on the product page size chart.

MSRP: $150


  • Weight: 14oz (400g)
  • Cargo capacity: 11.5L
  • Two 500ml (17oz) soft flasks included
  • Bottle holsters tighten with cinch cords
  • Stash mesh pockets outside bottle holsters
  • Dual large pockets on bottom front: one zippered, one elastic
  • Sliding rail sternum straps
  • Front side trekking pole loops
  • Double ice axe loops
  • Waterproof fabric around main compartment
  • Vertical stretch mesh rear pocket
  • External bungee cord to secure cargo
  • Dual zippered lateral pockets
  • Two pill pockets on front straps with waterproof backing
  • Vertical rear zipper pocket
  • Hydration reservoir compatible
  • Three size options, unisex sizing

Deep dive:

Just as its namesake ultrarunner has shifted focus a bit in recent years, the Ultimate Direction AK (for Anton Krupicka) Mountain Vest has also evolved from a minimalist race pack to something with extensive cargo capacity and numerous storage options to accommodate long days of exploration on or off trail. Impressively, the expansion of this pack’s size and functionality has come without the customary weight bump; one reason is the utilization of soft-sided drink flasks on this year’s model which replace the previous version’s hard plastic bottles.

Weight is also minimized thanks to fabric construction, which is comprised of three super lightweight materials: 1) 150g Mono Mesh on most of the interior surfaces, 2) 180g Power Mesh with stretch capacity on the side panels and most pockets, and 3) Silicone-impregnated 30D nylon protecting the primary rear cargo compartment with waterproof and tear-resistant strength. The mono mesh fabric is soft against your body and highly breathable to ventilate and move moisture, but there is no waterproof section of the interior surface; instead, the AK 3.0 has two small waterproof pill pockets on the front straps, but larger items like phones, maps, or cameras in strap pockets will be susceptible to some saturation.

One of the things we like best about this vest is the storage arrangement of the front pockets, which allow you to keep virtually all of your essentials within easy reach without having to adjust the pack. The soft flasks ride much more smoothly with less bounce than rigid bottles, and they’re located high enough on the chest that you can usually suck water from the flasks without having to remove them from the holsters.  There are external pouches on the outside of the flasks, pockets above and below the flasks, and large lateral pockets that are easy to access on the go. The AK 3.0 introduces front side trekking pole loops, which prevent the awkward overhead/backward reach to access or store poles.  Pole access is still tricky to manage without breaking stride, but it’s a lot more time efficient than having to take off your pack.

Storage on the back side of the back is outstanding also. The main compartment zips from two directions and is spacious enough to stash puffy jackets or other large gear, with a full length vertical stretch mesh pocket on top of it for food or additional gear.  Inside of the main compartment is a sleeve and a Velcro fastener for a fluid reservoir (not included) if you prefer that method of hydration. A drink tube can be routed through shoulder strap housing on either side, but there’s no place to attach the drink valve aside from tucking it under a sternum strap. To one side of the stretch mesh is a vertical zip pocket to keep your valuables in (this pocket is surrounded by the waterproof fabric) as well as a key clip. Crisscrossing the back side of the pack is an external bungee cord, along with anchor hooks placed further laterally than the main compartment to help tighten the cord down on the load of the main compartments to prevent movement.

The overall fit of the pack contours very nicely around the torso, as the lateral mesh pockets hug your sides, and cinch strap adjustments inside those pockets further minimize bouncing. Fit is adjusted in front by dual sliding sternum straps that can be positioned for comfort or maximal tension. We found that the pack is generously sized, so if you’re on the fence between sizes the smaller choice will probably suit you best.

Conclusion: The Ultimate Direction AK Mountain Vest 3.0 is an impressive update that adds a ton of storage capacity and improved ride comfort without compromising your ability to move quickly on or off trail.

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About Author

Donald is a physical therapist, California native, barefoot aficionado, and father of three with more than 25 years of experience in endurance sports. He was a collegiate rower at UCLA, then dabbled in marathons and Ironman-distance triathlons before falling in love with ultras in the early 2000s. His favorite locations to run include Marin County, CA, and the Sierra Nevada mountains, and he loves exploring America's National Parks. When he's not training for ultramarathons, he enjoys hiking or slacklining with his family in Monterey County, CA.

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