Do Dry Bags Float?

A roll-top dry bag floats if it is sealed with enough air trapped inside, but it is not a guaranteed life-saving float, so never rely on it for anything critical.

The reason a sealed dry bag floats is simple. When you roll the top down and clip it, you trap a pocket of air inside along with your gear. That trapped air makes the whole package less dense than water, so it tends to bob at the surface rather than sink. The more air you leave inside before sealing, the better it floats.

Where it gets less reliable is the load. Pack a dry bag full of heavy, dense items and you squeeze out most of that air, which kills the buoyancy. A bag stuffed with a phone, a towel, and a snack will usually float. A bag weighed down with a heavy battery pack or a thick coil of chain may not. Floating is a happy side effect of a sealed roll-top, not a rated safety feature.

So treat it as a nice bonus, not a flotation device. A dry bag is built to keep water out, not to save a person or hold a heavy load at the surface. If you want extra security on the water, clip the bag to your board or a D-ring so it cannot drift off if you take a fall, and never count on it in place of a proper personal flotation device.

If you want a roll-top bag that seals well and keeps your gear dry on the water, the NIXY 10L Waterproof Dry Bag uses a roll-top closure and a shoulder strap so you can clip it to your board and keep your essentials safe.

Frequently asked questions

Will a dry bag keep my phone dry if it falls in the water?

A properly sealed roll-top dry bag is designed to keep water out, so a phone inside should stay dry through splashes and short dunks. For full peace of mind, roll the top down at least three or four times and clip it firmly before you head out.

Why is my dry bag sinking?

Usually because it is packed with dense, heavy gear that has squeezed out the air, or because it was not rolled and sealed tightly enough to trap air inside. Leave a little air in the bag before you seal it, and avoid overloading it with heavy items if you want it to float.

Can a dry bag be used as a flotation device?

No. A dry bag is built to keep water out, not to support weight at the surface or save a person, so never use one in place of a personal flotation device. If you want it to stay with you, clip it to your board or a D-ring.