Hands-on Gear Review

Mountain Hardwear Sub Zero SL Review

Mountain Hardwear Sub Zero SL Parka
By: Ian Nicholson ⋅ Review Editor  ⋅  Apr 8, 2010
Price:  $295 List
Pros:  Warm and very water resistant.
Cons:  Bulky and heavy.
Manufacturer:   Mountain Hardwear

Our Verdict

This parka has been discontinued and replaced by the Mountain Hardwear Chillwave, which is has a moderately low warmth to weight ratio compared to other top parkas. See the Men's Down Parka Review to compare all of the models tested.

We've left the Sub Zero's review intact below. Note that it is now highly outdated and likely inaccurate.

If you need a serious jacket for extreme cold, this is the one. The Mountain HardWear Sub Zero SL wins our Recommended award because of the many functional features that make this a desirable jacket for mountaineering, such as a longer fit, a large hood, very water resistant material, and clever ways of sealing out wind and keeping in warmth. However, that means that this jacket is not very lightweight and does not stuff down into a compact sack like all the other jackets in this review. This is also why it does not receive the Editors' Choice award like the lighter and more versatile North Face Catalyst. If you are looking for a jacket for everyday use in the winter, consider The North Face Nuptse or Aconcagua jackets, which are still warm but less heavy duty and much less expensive. If you need a lightweight and packable jacket, compare the other alpine down jackets: Mountain HardWear Nitrous Jacket, Patagonia Down Sweater, or the MontBell Alpine Light Down Parka.

This is one of the warmest and most water resistant down parkas in our review. It is a great option for those looking for a fully-featured, heavy duty jacket. It features fleece-lined pockets, an internal water bottle zippered pockets, and its own stuff sack. It uses Mountain Hardwear's proprietary waterproof material. However, the jacket itself isn't waterproof because it isn't seam taped. All these features make it one of the bulkiest down jackets we tested. It is an excellent choice for colder trips. The weather resistant shell fabric makes it a great choice for Cascade volcano climbing and New England ice climbing.

Our Analysis and Test Results



The Sub Zero is extremely warm. It is by the far the warmest jacket in this review and is ideal for cold, snowy, and wet conditions. Mountain HardWear's Conduit SL material is very water resistant (but not water proof because of the lack of taped seams), which makes it a good jacket for mountaineering pursuits where you could be getting wet as well as cold. Like the Nuptse jacket, there are reinforced patches on the shoulders for added durability when wearing a pack.

The Sub Zero has many interesting and useful features. The fit of this jacket is longer than all the other jackets in this review, which is nice because it protects more of your body from the elements. There is a drawcord inside the jacket around waist level that can be pulled tight to keep wind out and seal in even more warmth around your core. There are Velcro closures around the wrist cuffs for the same reason. There is also an interior water bottle pocket, which is a handy feature for mountaineering when your water is likely to freeze.

In our Outdoor Gear Lab hose testing we determined that the Mountain Hardwear Sub Zero was one of the most weather resistant down jackets in our review. While no down jacket is great in the rain, the Sub Zero was about as good as it could get and repelled wet snow and a light drizzle better than we could have asked for. The hood is copious and fit all helmets we tested. We liked the face covering flap a nice addition that protected most of our face even on the windiest of days. The Sub Zero is also one of the few baffled jackets we tested, a design that adds quite a bit of expense but greatly increases the warmth of the garment.


The same features that make it one of the warmest and most water resistant parkas in our review also make it one of the bulkiest and heaviest. Part of this is the heavy Conduit shell, which is exceptionally water resistant but heavy. It was the heaviest jacket reviewed, weighing in at 1 lb 10 oz. (an entire pound heavier than the Mountain Hardwear Nitrous Jacket), and it is the only down jacket in this review that does not stuff down either into a pocket or a stuff sack. However, these complaints come with the tradeoff of the Sub Zero being ridiculously warm. If you are looking for a jacket for extreme conditions, the weight and packability hardly matters. The Sub Zero does have a lower quality down than most of the other jackets, using 650 fill down rather than 800 fill down like the Patagonia Down Sweater, the MontBell Alpine Light Parka, and The North Face Catalyst jackets. This lower quality down is partly what makes the jacket so bulky and heavy — if it was made with 800 fill down it would most likely be lighter but also far more expensive.

I am not sold on the detachable hood. If it is necessary to wear a jacket that is this warm, a hood would be wanted as well, and it doesn't seem to add much functionality by being able to take it on and off. The zippered seam where it detaches is just another spot where wind can leak into the jacket. The Velcro closure in the front of the hood is nice because it closes in front of your face to keep your chin warm, however a gap is left under the Velcro and wind comes right in. It would be warmer and more functional if is actually sealed closed in some way in front of your face. If you want to save a bit of weight and do not like having a hood, this jacket is also sold as a non-hooded option.

The fleece-lined hand warmers are nice for wearing around town but add weight for applications where you want to move light.

Best Application

As one of the warmest jackets we tested, it is a great option for cold weather camping, mountaineering, ice climbing, and skiing. A little too warm for summer camping.


This jacket isn't cheap. However, you are paying for a thick and warm jacket with a water resistant fabric. The non-hooded version of this jacket is not made with the Conduit SL material and is significantly less expensive — $185 — which is even cheaper than The North Face Nuptse.

Ian Nicholson

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OutdoorGearLab Member Reviews

Most recent review: January 28, 2014
Summary of All Ratings

OutdoorGearLab Editors' Rating:  
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Average Customer Rating:  
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67% of 3 reviewers recommend it
Rating Distribution
4 Total Ratings
5 star: 25%  (1)
4 star: 50%  (2)
3 star: 0%  (0)
2 star: 0%  (0)
1 star: 25%  (1)

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   Jan 28, 2014 - 10:12am
spauldeagle · Backpacker · michigan, florida, georgia, seattle washington

I found this Jacket very warm. sometimes too warm if you are active. I can see how one may become cold in negative temps while sitting still waiting for a photograph, but this can be caused by multiple heat regulating principles and layering inefficiencies. I have been in deep negative temps multiple times -30s most recently ice fishing in -27 for over 8hrs. theres not much movement ice fishing. I would like to add that the jacket has conduit fabric (mountain hardwares old proprietary waterproofing membrane, which proved to be a blessing on a 4 night high alpine trip into the wind river range with a group of experienced back country friends. by the 2nd day i was the only one not saturated, cold, miserable and ready to pack up and leave. this jacket is one of the go too jackets for expeditions to rainier by the local outfitters. my fiancé likes to jack this coat a lot during the winter.. looks like ill get her the women's version.

Bottom Line: Yes, I would recommend this product to a friend.

Person Icon

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   Jan 25, 2013 - 03:55pm
The name definitely does not match warmth of this jacket. I tested this jacket extensively while working on a photo project in every day for a month in "sub-zero" Harbin, China". I was extremely disappointed to say the least particularly since it was made from such a reputable company like Mountain Hardware.

I had to wear 2 more down jackets (The Northface Summit series lightweight down jacket and the Patagonia Bivy Down jacket..) underneath the supposedly Sub Zero jacket just to keep warm. I should like to add that you don't test a down jacket by wearing it for just 5-10 minutes with a t-shirt on. I tried that routine and yes it was possible to stay warm for that period of time but after 15 minutes I began to get really cold. I tested this jacket alone, with one down jacket underneath and finally two jackets underneath. I tested this jacket with various layers and combinations of insulation underneath (heavy weight fleece, light weight fleece, etc. etc. etc. ) and most importantly I tried this jacket with numerous different combinations under REAL conditions of -25 Centigrade (-13 F) for 4 - 6 hours straight outside. THAT's how you know if a jacket works or not. The thing that really annoyed me was that with the just this jacket alone and a couple layers of fleece I should of been warm for a hour outside. I was cold usually after 20 minutes. I highly highly do not recommend buying this jacket if your serious about wanting something that will keep you warm in freezing temperatures.

Bottom Line: No, I would not recommend this product to a friend.

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   Sep 20, 2010 - 12:05am
Srbphoto · Climber · Kennewick wa

After moving to Eastern Washington from California I decided to get a down jacket. We have dry, cold weather (lows from minus to 20's on a consistent basis)and I like to walk to work and take pictures in the winter. In California, I never felt the need because winter for me was being in rain for long periods of time and it isn't that cold. I bought mine (still with the tags) at the REI garage sale. It was in the garage sale because the hood was stolen.

I have had mine for about 3 years. I really like it. I have been hiking with the temp in the teens with just a base layer on and have been comfortable. I have stood around in single digits and been fine. I do not miss the hood. I'm not sure I would use it unless I was in a real blizzard.

The one drawback for me is it is SO warm. I almost can't use it for any activity unless it is under 20 degrees. But it is awesome for being outside for extended periods with little to no activity.

If you are someone who gets cold easy or won't be very active in cold weather- 5 stars. If you are going to be very active (unless it is really cold) it might be too warm. That's why the 4 stars.

Bottom Line: Yes, I would recommend this product to a friend.

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