What Is a Dry Bag?
A dry bag is a waterproof bag that seals by rolling its opening closed. No zip, no seam to leak — just a folded, clamped barrier between your gear and the water.
A dry bag is a waterproof bag with no zip: you fold the stiffened opening down against itself three or more times and clip it, creating a sealed, air-trapped barrier. Rolled correctly, a welded-seam dry bag keeps contents dry through rain, spray and brief immersion, and floats if it goes overboard.
How does a roll-top dry bag seal work?
The top of a dry bag is a stiffened band. You press the opening flat, fold it down against itself three or more times, then clip the buckle so the folds cannot unwind. Each fold traps a layer of air and doubles the path water would have to travel to get in. The result is a closure with no mechanical parts to corrode, jam or wear out.
The air you trap in the roll also gives a sealed dry bag buoyancy — which is why a bag that goes overboard usually floats rather than sinks.
Fabric and seams matter more than the label
Waterproof fabric is only half the story. Most failures happen at the seams. A stitched seam puts thousands of needle holes through an otherwise waterproof panel; a radio-frequency welded seam fuses the material into a single continuous barrier with nothing to leak through.
The TECTON Expedition System uses 420D TPU laminated ripstop nylon with RF welded seams and a reinforced abrasion-resistant base — the areas that take the most punishment on a boat deck, a riverbank or a tray.
Common questions
Are dry bags fully waterproof?
A well-built dry bag with welded seams and a correctly rolled closure is waterproof — it will keep contents dry through rain, spray and brief immersion. Waterproofing depends as much on how you close it as on the fabric.
Can a dry bag be submerged?
Roll-top dry bags are water-tight rather than pressure-rated. Rolled three or more times and buckled, they handle accidental submersion such as a capsize or a dropped bag. They are not designed for prolonged or deep submersion like a dive case.
What is the difference between a dry bag and a waterproof backpack?
A dry bag seals by rolling its opening closed, so there is no zip to fail. A waterproof backpack prioritises carrying comfort and access, usually with a water-resistant zip. Many people carry dry bags inside a pack to protect specific items.
What should you put in a dry bag?
Anything that ruins a day when it gets wet: phone, keys, wallet, camera, a spare layer, first aid, food, and dry clothes to change into.
Choosing your size
Once you know how a dry bag works, the only real decision left is capacity. Most people underestimate how quickly a bag fills once you roll the top down three times.
Read the dry bag size guide for what actually fits in 2L, 5L and 10L.
The TECTON Expedition System
Three purpose-built waterproof dry bags — 2L, 5L and 10L — engineered to work together as one modular system. Designed in Australia.