35L Roll Top Waterproof Backpack for Hiking and Kayaking

The 35L Roll Top Waterproof Backpack for Hiking and Kayaking is a pack Sealock supplies to OEM and wholesale buyers who need water gear that also wears well on a long trail. We build the shell from 420D TPU with RF-welded seams, rated IPX7, and what sets it apart from a plain dry sack is the built-in air-release valve and a real ergonomic harness. At Sealock we have spent years on exactly this combination — keeping a bag fully sealed while still letting a paddler purge the trapped air and shrink the load.

Most waterproof backpacks trap a balloon of air once you roll the top shut, leaving you fighting a stiff, oversized bag. We build in a sealed one-way air-release valve so you can press the pack flat and push the excess air out without ever breaking the waterproof seal. The result is a smaller, denser load that sits closer to your back, packs faster into a kayak or canoe hatch, and carries more comfortably. It is a small part, but on a rafting or paddling trip it is the detail people notice first.

The body is welded, not sewn. Using HF (high-frequency) welding, we fuse the 420D TPU panels into a continuous waterproof shell with no needle holes, then the roll-top closure folds down to lock the opening. We test this construction the way a dry bag should be tested — under external pressure equivalent to roughly 1.0 Bar, consistent with the IPX7 rating — so the pack holds out water during river crossings, capsizes and sustained rain, not just light splashes. This is the standard we hold every roll-top waterproof backpack on our line to.

A waterproof shell is only half the job; a 35L pack also has to ride well once it is loaded. This one uses a full ergonomic system rather than the minimal straps you find on a basic dry sack:

Each pack starts as cut 420D TPU panels. The seams and the valve seat are HF-welded first, the harness and ventilated back panel are assembled, then the roll-top and reflective prints are finished. Before a batch leaves the floor we sample-test the welded shell under pressure to confirm the IPX7 seal, check that the air valve seals fully after purging, and pull-test the shoulder straps and waist belt at their anchor points. We would rather reject a unit here than have a paddler discover a weak seam mid-river.

As the factory, we support OEM and ODM on the 35L Roll Top Waterproof Backpack for Hiking and Kayaking from an MOQ of 300 pcs: custom colours beyond the standard yellow and green, your own logo, harness adjustments and valve placement. Tell us your target market — paddling, fishing or general outdoor retail — and we will spec the pack and quote against it. For brands building a waterproof line, this model pairs well with our roll-top dry bags and duffels in matching materials.

Every shipment goes through pre-delivery QC, with replacement for any genuine welding, valve or material defect found on arrival. Orders are documented from sampling to final inspection, and our team stays available for re-orders, spec changes and packaging requirements.

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Sealock (YiFuLong Outdoor Gear Co., Ltd.) has built welded waterproof gear in Guangdong since 2003. To order the SL-E801 in 35L, or to start an OEM/ODM program, send us your sizes, colours, logo and target quantity for pricing and lead time. MOQ 300 pcs · samples 7–15 days · production 30–45 days.