|A 10L SeaLine dry sack with paracord shoulder strap.|
- They'll also float, unless you load 'em up with exceedingly heavy stuff--lead or something similar. Filled with air, they'd certainly help you stay afloat if needed.
- You can smoosh out the air to compress clothes, sleeping bags, etc. in a vacuum-bag like fashion. Not as good, but certainly some added compression over a normal stuff sack.
- The tough vinyl offers an extra measure of protection from abrasion.
- You can also use it as a water container--it'll hold around 10L of water, which could be a life saver in a survival scenario.
- Emptied of gear and filled with air, they'll also make a decent air pillow.
The 10L dry sack is big enough to carry a basic survival kit like a Dave Canterbury style 10-piece kit. While a basic, shoulder-bag sized survival kit has its limitations, this is certainly an good kit to have on a short hike, scout, etc.
While I prefer backpack carry in most cases, I know there are many who like shoulder bags and old-school haversacks. Due to the waterproof nature of these dry bags, I think they make a superior gear option for that kind of kit, especially if you're going to be on/near water.
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NOTE: The Marines are using a similar bag--a bit more high tech--called the MAC Sack, also made by SeaLine. It has a built in air purge valve to help with the compression. I don't have any first hand experience with the MAC Sack, but the reviews are very good.