Tents, sleeping bags, and backpacks are the primary pieces of gear that tend to preoccupy backpackers. This focus is certainly appropriate, as these pieces of equipment can certainly make or break a trip if they don’t perform as needed or fit properly. I spent an inordinate amount of time researching these items when I first got into backpacking and thought of many of the “accessories”, such as stuff sacks, were simply gimmicky add-ons that I could postpone purchasing or forego altogether. This worked well for my first few years of backpacking with entry-level gear and I did pick up a few stuff sacks from a clearance bin along the way and found myself pleasantly surprised at their utility.

Once I invested in a high-quality down sleeping bag, it seemed a wise choice to protect my investment when backpacking with a waterproof compression bag.

The Sea to Summit eVent compression dry bag appeared to be the best product on the market (and much better than the stuff sack included with the sleeping bag by the manufacturer) so I bought one, size medium for a 15 degree down bag, and never looked back. I’ve used this compression dry bag for over five years and when I added another sleeping bag to my quiver I immediately bought a smaller version of the same compression dry bag for that sleeping bag as well.

The Sea to Summit Evac eVent Compression Dry Bag

The Sea to Summit eVent compression dry bag comes in a variety of sizes that hold different volumes, and is currently offered in 3 versions: a lighter weight UL version, their middle of the road regular / standard option, and lastly a heavy duty (HD) version. Weights seem reasonable for a durable and waterproof piece of gear that will completely protect its contents. The UL version weighs anywhere from between 2-3.9 ounces depending on size. Sea to Summit frequently updates their compression dry bag lineup, changing size options, weights, and product naming.

If you're looking for an even lighter weight compression option, Sea to Summit also offers their Ultra-Sil Compression Sack, but this does not utilize the eVent fabric as can be found in the compression dry bags in this review. I've used several sizes of the eVent versions to fit everything from a 30 degree, 900-fill down sleeping bag (Marmot Plasma 30) to a 15 degree, 800-fill down sleeping bag (Marmot Pinnacle), and a 0 degree, 900-fill down sleeping bag (Feathered Friends Snowbunting EX 0).

While the lineup is updated frequently, the basic principle remains unchanged. This is a simple, functional product made of high-quality materials. While the outside of the oldest dry bag has some stains and superficial scars that testify to its frequent use, the inside is nearly pristine. The stitches and tape on the seams (double-stitched and seam-taped to ensure the 70D nylon body has no weak spots) look almost brand new even after over 200 packings and unpackings on trips ranging from sweltering to subzero, from high desert in Arizona to temperate rainforest in the Great Smoky Mountains.

While no piece of gear can make a 15 degree sleeping bag become the size of a tennis ball – and for the sake of the down and the bag itself, this wouldn’t be desirable – the Sea to Summit compression dry bag easily renders it to the size of a cylindrical soccer ball. A 30 degree down bag in the compression bag easily packed down to become not much larger than a two liter bottle. Having the bag compressed helps immensely with getting these bulky items into a backpack and making the most of the limited space available. Just as valuable, in my experience, is the peace of mind that is provided by knowing that regardless of daylong rains or accidents with water (such as a leaking Camelbak or Platypus) the sleeping bag will be as dry when it is taken out as it was when it was put in.

The wide mouth of this compression bag makes it easy to fill it with large, lofty sleeping bags and the breathable bottom, which is made of eVent fabric that allows air to pass out of the stuff sack while still remaining waterproof, makes getting all the air out and compressing it incredibly easy. Depending on the shell of the sleeping bag, getting the air out can be a bit more involved but this is just a comment on the process of compressing gear in general and the varieties of shell fabrics, not an issue related directly to the Sea to Summit compression dry bag. If you’re using a smaller sleeping bag with a larger compression dry bag, you might have room to throw in a down jacket or down booties as well. The roll top lid is intuitive, buckles securely and the four straps allow for everything to be evenly and quickly compressed. The bottom of the compression dry bag has a “handle” (really just a strap of fabric with the eVent logo on it) that allows for it to easily be retrieved from the pack when you arrive in camp and begin unpacking.

I’ve never had a catastrophic accident with the Sea to Summit compression dry bag, such as dropping it in a lake or leaving it out in a thunderstorm, but I have had it in enough “normal” backpacking conditions and around enough moisture to know that it performs as advertised. Major water bottle spills aren’t even minor issues with this compression dry bag and on rainy multi-day trips where pretty much everything becomes saturated to some degree with moisture, this stuff sack serves as a safe haven for one of the most important backpacking items.

While Sea to Summit explicitly states that the compression dry bag is not intended to remain waterproof if submerged, I decided that it would be interesting to test its performance in a worst case scenario. What I discovered was after repeated submersion and being placed under running water, there was a minimal amount of leakage through the top (at the point of closure) but overall I was impressed by its ability to keep water out. The sleeping bag inside would certainly have been usable without any issues…my sleeping bag has gotten more wet from just spilling a bit of a Nalgene on it or condensation overnight. This certainly isn't a "deal breaker" characteristic for a compression dry bag and given my satisfaction with its real-world performance it seems to me that this item performs extremely well under normal conditions and impressively under adverse (and unintended) conditions.

Although there isn’t really any specific double-duty that this product can perform, I have often stuffed the clothes I’m not wearing into it at night and used it as a pillow. This works well and also helps with organization as my clothes (other than wet or damp ones) are all in one place and protected from any moisture that might land under the tarp, build up on tent walls, or spill out of an improperly closed water bottle.

The Sea to Summit Evac dry bag lineup offers a variety of sizes, with one likely working well no matter your packing application.

Conclusion

Overall, this product approaches perfection and is one piece of gear I wish I’d bought sooner. It has greatly simplified my packing process and eased my concerns about my sleeping bag getting wet. Having these large items reduced to a manageable size is great and although there are cautions about compression damaging down sleeping bags, my experience with this has been unnoticeable and inconsequential. However, I do not leave the bags compressed for any longer than necessary. They are compressed the day of the trip and unpacked as soon as the tent is set up. Two of my sleeping bags have been through this cycle more than 100 times each and I have not noticed any performance issues.

The product might be a bit too heavy for superlight or ultralight or superultralight backpackers, but Sea to Summit does offer an Ultra-Sil version (non-eVent) made with a lighter 30D fabric and less robust hardware. All utilize a similar design and may be of interest to many readers. In regards to the ever present backpacking weight to durability tradeoff however, the experience I’ve had with the 70D version reviewed here has been entirely positive. I would recommend this product without any hesitation for lightweight backpackers, and especially those who have a bit of anxiety about water and down.

The eVent Compression dry bags from Sea to Summit come in a variety of different sizes and lineup options (UL, standard, and HD) priced between $40 and $90. Take a look at the UL version here at Backcountry.com, and you can check out all 3 versions here at Amazon.com. For the non-eVent Ultra-Sil option, you can take a look here at REI-Co-op.

Editor's Note: This article originally appeared in Issue 32 of TrailGroove Magazine. You can read the original article here for additional photos and content.