S29 AllWhite Ursack Bearproof Bear Bag Review

Ursack Bearproof Bag hanging from a tree. There's no need to hang it 10 feet off the ground and 5 feet from a tree trunk because the bag is made out of super strong fabric.
Ursack Bearproof Bag hanging from a tree. There’s no need to hang it 10 feet off the ground and 5 feet from a tree trunk because the bag is made out of super-strong fabric that bears can’t penetrate.

Note: This product has been replaced by the new Ursack AllMitey bear bag. Please read my Ursack AllMitey Review for the complete lowdown. 

The S29 Ursack is a soft-sided bearproof bag that you can use to store your backpacking food and smellables in at night. They’re different from a traditional bear bags that you hang a minimum of 10 feet off the ground and 5 feet away from the trunk because they’re made out of a bear-proof fabric reinforced with Spectra yarns that bears can’t chew or claw through, even if they get their “hands” on it.

This means that an S29 Ursack can be tied to a stationary object closer to the ground like a low hanging tree limb, all within arms reach, making it much easier for hikers and campers to use than hanging a bear bag the old-fashioned way by throwing a rock over a tree branch. While some national parks still require the use of hard-sided canisters, Ursacks are IGBC approved and have proven to be effective against eastern US black bears.

Personally, I’ve pretty much given up hanging bear bags on backpacking trips and use a 7.7 ounce S29 Ursack or a hard-sided bear canister on all of my backpacking trips because they’re so much faster and more reliable than hanging a bear bag from a tree. The time-to-weight tradeoff is worth it for me. I’d rather hike another hour, have more hangout time in camp, or just go to sleep an hour earlier, than worry about finding the perfect tree to hang a bear bag.

When you get right down to it, most backpackers and campers are pretty bad at hanging bear bags in the manner prescribed by the US Forest and Parks Service. Some would argue that these old-fashioned bear bagging techniques are outdated anachronisms that don’t withstand careful scrutiny in the face of increasing recreational use in our wilderness lands. I’ve so seen so many terrible “hangs” by other backpackers, that it’s probably better for the bears if all campers and backpackers stop hanging their food and use Ursacks, bear canisters, or pre-placed bear lockers exclusively for camping food storage, at least east of the Mississippi River in the US.

The S29 All-White Ursack
The S29 AllWhite Ursack

The S29 AllWhite Ursack

I recently bought the updated S29 AllWhite Ursack to replace the older V27 Ursack I’ve been using since 2007.

The difference between the newer S29 Ursack and the older V27 Ursack (formerly called the Ursack TKO) is the number of yarns of Spectra per inch woven into the bear bag fabric: the new S29 has 29 yarns per inch which is somewhat stronger than the older V (for Vectran)  model which had 27 yarns per inch. Spectra yarns are high-performance polyethylene fibers that are stronger than steel and used to make body armor and automobile airbags (see Wikipedia for more details).

Instructions for how to knot and hang the bag are printed inside the Ursack
Instructions for how to knot and hang the bag are printed inside the Ursack

Plastic Sack Liner

Ursack recommends that you line the S29 with a large, odor proof OPSack plastic bag (weighing 1.3 ounces). While there is some debate about how smell proof these bags are, I like lining my Ursacks with OpSacks because they can stand up to the abuse of weeklong backpacking trips and help contain the crumbs, and leftover or leaking fluids, including oil from the olive oil packets that I carry for convenience and extra calories on long trips.


I’ve been using Ursacks to hang my food at night for going on 10 years and can’t think of a better, more foolproof way to protect it from bears. Carrying a soft-sided Ursack is so much easier and more comfortable than lugging around a bear canister, and the time savings over trying to hang a bear bag in the dark is the clincher for using an Ursack instead of a bear bag.

Disclosure: Philip Werner (SectionHiker.com) paid for this product with his own funds. 

SectionHiker is reader-supported. We independently research, test, and rate the best products. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.


  1. Nice review but I’m not sure that I would agree that it takes “hour or more to hang a traditional bear bag”. I use the PCT method and would guess it usually takes us around 10 minutes. However the tree selections is pretty good down here in PA.

  2. ‘Had one since I did the NPT through hike a few years ago. I like it. No complaints.

  3. I’ve wanted one of these for a while but to echo the other comment how can it take an hour to hang a bear bag. In the 80 nights I’ve been backpacking in mid atlantic the last 4 years I can think of 1 time when it took more than 10 minutes.

  4. The one thing about not hanging the Ursack higher is the mauling factor. Sure, the bear might be thwarted from actually getting the food, but the food may end up as a crumbled, mashed mess. That’s the thing that’s kept me from buying the Ursack (although I could definitely see the convenience of it with smaller critters in areas where bear encounters are unlikely).

    • “You mean to tell me you didn’t want your food smashed? Hrmph. The nerve of some people!” – bear

      • Hey Smokey, I gotta agree. There’s plenty of berries for us to fill our bellies with this year so I just do this to piss off the people. So funny to watch them try to make coffee with smashed up grounds. Ha! Kinda makes up a little for them invading our territory–although I really kinda like the change of pace and most of them are decent neighbors. Every now and then I get a stupid one and I get a tasty meal too–that is a bonus. Damn, these humans eat good!

        One of these days I’m gonna make growling noises and charge one of these idiots. If I can get them to pee their pants it’ll all be worth it.

    • They do have a hard aluminum liner that will prevent crushing – though it adds another 11 ounces.

  5. Use to use the hard plastic bear vault because many places I hike required it. Made the switch to Ursack last fall and love it…although now I have to find a way to keep my crackers from getting smashed :). At first I was also bothered by the volume mismatch you mentioned…but then I decided to add another plastic liner (aka freezer bag) to store my stinky trash. so now I am okay with it. I like the idea of having a spare so might buy another!

  6. Great review! I use the older Ursack and have been happy with my switch. Even at ten minutes for a proficient PCT hang, Mike’s 80 nights equals 800 minutes or 13 hours and 20 minutes that could have been used for another outdoor activity. I’m with Phil, I like being able to walk over to a tree and tie on my Ursack. Done!

    BTW, the Ursack shown hanging from the limb is improperly tied as there should be no slack between the two knots. Double overhand, around the tree, and a final square knot.

    Also, the recent re-test of the Ursack using real grizzly bears was successful. Over a 2-hour period none of the seven attacking bears were able to breach the Ursack.

  7. Not to be a killjoy, but readers should note that there are a few areas in Sequoia and Kings Canyon plus all of Yosemite where Ursack is still not allowed. Hard sided containers are still required in these locations. If you are headed to these areas, double check the Ursack and particularly the Park Service websites for the latest requirements or allowances. The Ursack site has a thorough description of the ins-and-outs of their wrangling with the agencies over time. Their purchase page notes possible restrictions as well.

  8. I purchased the new S29 All White Ursack two weeks ago. It shipped with a 650 cubic inch 12.5″ x 20″ LOKSAK by OPSAK. I filled the LOKSAK with water, and it completely fills the Ursack. You can see photos of it at my Picasa website: picasaweb.google.com/neuswangerk/UrsackAndLOKSAK

    I measured exactly 11 quarts of water in the LOKSAK, which is 670 cubic inches: exceeding the stated capacity.

    (By the way, the LOKSAK is NOT intended to be hold 23 pounds of water!)

    My only slight complaint is the melted tip of one end of the rope came unfrayed after one weekend of use, but that can be easily remedied.

    As someone who has camped in Colorado’s mountains for 35 years without hanging my food, I have never had a bear encounter. So I tend to be skeptical of the danger, but as my friend pointed out, you’ve worn your seatbelt for 35 years and never needed to use it. Yet. So now I protect my food. And the Ursack is, for me, more protection than I expect to need (since I don’t expect to go to Yosemite).

  9. I’ve been using various versions of the Ursack since maybe 2007. I haven’t tried the All White, but in general, I’m very pleased with the Ursack line. That said, when I’m in Sequoia or other heavy bear areas, I use a canister. The true advantage of the Ursack is only really appreciated once you’ve had to lug a canister around.

    ColoradoHiker, were you aware that testing has shown that the LokSak is ineffective against bears? In tests, airport type dogs were able to detect food odors consistently in lockers containing a loksak (sealed with the food inside) vs. lockers with no food.

    In other words, there’s no point in carrying a Loksak if one is trying to “hide” food scents from a bear. It just doesn’t work. The Loksak will protect your Ursack from food leaks, so maybe there’s some benefit there.


    • If a bear is within a foot of your food bag (like BPL’s dogs) then you’ve lost. OPSacks can greatly reduce odors so bears further away (the vast majority) don’t take notice.

  10. These things are bear proof but what about mouse proof?

  11. They makers only say critter resistant (and only say bear resistant). I have an older model and mice did manage to chew a hole in mine – they didn’t have enough time to get in however.

    • I had a marmot work on my older style Ursack for ~8 hrs last year (hung off a rock as there were no trees at that elevation). It couldn’t completely chew through the bag, but it’s teeth got through in many places (threads in the weave were displaced) and poked holes in packets of mayonnaise, powdered drinks, etc., and it crushed lots of my 8 days of food. I’d have been better off if I’d used the aluminum liner.

      As my old bag was pretty beat up, I bought the S29 model and also have complaints about the shoddiness of the unfinished holes as well as the new tie off method. It doesn’t seal the bag as well as the old bags sealed and I’m quite certain that field mice could get into the small opening that remains no matter how hard I tighten down the knot. Just the same, I’ll carry it over a bear canister any day and expect it to protect my food from most rodents and birds.

  12. Thanks for the great review. I will be looking into purchasing one of these based on your review, I just hate the color white, it is like Beacon on a dark night in a Forest of Green, not good for stealth camping, but I could put my Sleeping bag cover over it so it does not stand out….For those individual Olive OIl Packets issues, I suggest you read my post about re-using or recycling personal medication containers for storage of said products. Haven’t had an “accident” in years since I started using those containers and you can put the used packets back into the container to haul out with you…or as I do, I use Laboratory grade bottles to premix my Olive Oil, Vinegar and spices dressings which I put into the Medication bottles.I like pure Olive Oil on MRE Biscuits and Bread but not crackers so I carry the individual packets as well in the recycled containers as suggested above….. P.S. Rut row…..REI, Campmor, Cabelas, nor Bass Pro Shop do not carry the S29 Ursack via their websites less than two minutes ago….So was this a “Proto Type” they gave you to test???.

    • Eddie, you pretty much have to buy from Ursack although there may be some resellers. “Mass market” shops like REI, etc. don’t carry high end or specialized items.


    • Mr Google says that fabric resists dyes so white is the option you have, however, seasoned bear slobber may eventually acquire a greenish tinge…

  13. I just went to Ursack and ordered the S29 and the Opsack. Planning to do more of the AT and frankly am getting real tired of trying to find the right tree to hang my bag. I realize that many of my fellow AT hikers don’t even bother hanging their bag, I am an ultra light backpacker so extra ounces do mean something however, I don’t mind the extra few ounces if it means I feel my grub is more secure, is easier to secure, and at least discourages the smaller critters.

    • REI is carrying a Ursack for fending off field mice and other small critters,. I guess you store your Toothpaste and soap and such in the bag they are selling…

    • I just checked REI again and they have a “Ratsack” by Ursack the Large bag they say has a 2500 cu.inch capacity and weighs 10.5 oz. and will contain 23 pouches of freezed dried bags. They claim the small bag holds 5 days worth of food at 1,200 cu.in. But they do not carry the S29 version…$36.-$48 at REI I’ve been using an REI container since they first came out but this bag looks interesting. Has metal sewn into it..

  14. Been using one for 5-years without any troubles. Only thing I did was put brass gromets in the holes and whiped the line ends. Still tie it at least a hundred yards away from my camp – well away from any trail and never at ground level.

  15. Spot on review Philip. I have converted. I too have had a long time on occasion to hang my bear bag. The thing is to do it correctly takes some time. I think many toss it and forget it. It also boils down to pure luck sometimes. The wick burns out eventually.

  16. Read this because I just bought an Ursack for rodents more than bears. Also got a Dutch “Big Carl” cord to hang it with.
    Off-hand I don’t know if I got the same S29 or not (mine is more of a yellow-white) but I don’t recall seeing the extra 2 holes, I’ll have to look. Also I will look at the cord ends the see if they are fused or not or even can be.
    I did note the difference in size between the Ursack and the Opsack but I seen a miss-match like that so many times I didn’t think anything about it.

  17. I just wanted to let everyone know that the Ursack S29 All White is now approved by the Inter-agency Grizzly Bear Committee (IGBC) and most many parks follow the IBGC approved canisters. The Ursack is approved in The Tetons, Glacier, Denali, Wrangell St. Elias, etc.

    It is still not approved in Yosemite or SEKI however.

    I am looking into using 2 of these for a future trip to Alaska where I will need to carry 12-14 days of food. I carried 11 days in a Bearikade Expedition in Gates of the Arctic National Park this summer but while the Bearikade was approved there, it is not in Wrangell St. Elias NP, so I need a IBGC approved replacement.

  18. I got this in spring 2015 after months of research while being laid p in the hospitol for a collapsed lung. Living and camping in northern MN I encountered enough black bear in a summer for a few people, one of wich wandered thru my yard almost nightly for three years..listening to one sniff and paw the ground next to your head is very uncomfortable, even while in your own home. Regaurdless I felt the ur sack was the way to go for me for the simple fact that as I ate food it got smaller and took up less space in my pack as apposed to the bear canister.

    In the past I all ways sunk my food in the lake..as you can’t walk two miles in any direction here without finding a realtively sizable body of water.

    when I first got the ursack, I was disappointed because it appeared to not close and, my how does two double overhand knots stop a friggin 400 pound animial (about the size of the bear I saw 5 times last summer near my house) until I actually got my father to hold the bag while I twiseted it shut once to stress the fabric and totally clsoed the bag, it worked snese then. Also the knot, I tied it and we yanked on the bag and it took driving a screwdriver into the knot to loosen it, that roughly only 300 pounds of force having been exserted on it, I being 120ish my father being 180ish


    has an offwhite bag for small critters and the all white bag for bears, small critters can get into the bear bag and bears can get into the critter bag..there is no win win here other than the bear canister. I however felt that my ursack was more than sufficent, was a little disappointed with the unfinished/grommeted holes in it, until I actually pulled on it enough to tighten the bag and saw how the grommits could actually negatively effect the performance of the product by allowing an opening for a tooth or a claw.

    also the op sack is a bit poorly made, it only survived 2 days with my girlfriend befor she ripped the top flap off while opening the zipper.

    • I know what you mean about the zipper of the Opsack – it’s very easy to rip off and then the bag is almost impossible to open. I’ve learned to be very gentle with them…

  19. We have a couple of Ursacks – one older model (green) and the newer white version – that we use here in BC. I didn’t know about not hanging the bag next to the trunk – that’s usually how we store ours as we’re frequently in the (sub)alpine where the tree branches aren’t very substantial. We’ve even relied on sturdy little krummholz firs :-)

    Watching the demo videos has allowed me to sleep easier at night, though I still worry about mice getting in through the top (especially when sleeping in a hut!). I’ll usually stow my pot and/or lid just inside across the top of the Opsack to make it less inviting. Will have to watch the marmots though – there are a couple of places we go where they are infamous for going after hikers’ food!

    Tying one around a tree can still be a 2-person job, especially near the beginning of a long trip – one to hold the bag up so the other can take up all the slack and tie as close to the opening as possible :-)

  20. I have spent a lot of time working and recreating in bear country and have had a grizzly pass through my camp in the middle of the night, even with our food hung 1/2 a mile away. I get that this is pretty rare and it’s very unlikely that a bear ever comes to check out your food situation, however, if they do, do you want them to spend an hour messing around with your bear canister or Ursack even if it is an appropriate distance away from your camp? I’d rather have an out of reach bear hang where in the case that a bear does come to check it out, they would be much more likely to quickly move on. Even though these things keep your food safe from bears, I have no interested in increasing the likelihood that a bear is going to hang around the vicinity of my camp or be there playing with my bag of food when I go to retrieve it. Ursack’s website boasts about the amount of time bears spend unsuccessfully trying to get into the bags. Even though it’s unlikely that a bear will ever come to chew on the bag, hard pass. My vote is for a correctly done traditional bear hang.

    As for those that don’t bother with securing food from bears at all because they’ve never had a problem in the past, that’s reckless and don’t advertise your recklessness on the internet for naive hikers to follow in your footsteps. There is a lot of bad information on the internet about safety in bear country and what to do in a bear encounter, don’t add to it. If you are going to spend time in bear country, it is your responsibility to keep your food out of a bear’s reach, not just for your own benefit. Failing to do so puts other people at risk as well as the bears.

    Not only are we increasing our presence in bear habitat, but bear populations are growing and their food supply is not necessarily growing with them. Any inconvenience of making a bear hang is worth it. Always.

  21. Hi Philip: I use hard-sided bear canisters to defeat both large and small critters but the “Ursack AllMitey Bear Bag” looks intriguing. Have you had the opportunity to use the AllMitey and what are your impressions? Thanks, Jon

Leave a Reply

Your email address will not be published.