Sea to Summit Big River Dry Backpack
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Big River Dry Backpack
Dry Pack · Paddle Sports · Motorcycle Touring · Waterproof
A comfortable way to carry your gear along on any adventure. Big River Dry Backpacks are reliable, abrasion resistant, and waterproof. From the white water to alpine motor bike trails, this backpack keeps everything dry, together, and safe. A white interior laminate makes it simple to find your gear, while the oval shape and lash loops allow secure stacking or attachment to equipment. The hypalon non-wicking roll-top closure keeps water out, and the Field Repair Buckles can be replaced in seconds with just a Phillips screwdriver. So gear up, roll down and get after it.
10000mm Waterproof
10,000 mm hydrostatic head — fully waterproof for whitewater, submersion, motorcycle rain, prolonged wet exposure.
Built Tough
Heavy-duty 420D ripstop nylon + triple-coated oval base — abrasion and puncture-resistant.
Roll-Top Closure
Hypalon non-wicking roll-top with Field Repair Buckles — reliable seal, replaceable buckles.
Field Repairable
Field Repair Buckles replaced in seconds with just a Phillips screwdriver — no special tools needed.
Multi-Activity
Paddle sports, motorcycle touring, wet-weather commuting, canoe expeditions, alpine adventures.
3 Sizes
30L for day trips, 50L for weekends, 75L for week-long expeditions.
10000 mm Hydrostatic Head (NEW — WATERPROOF RATING)
The Big River's fabric has a 10,000 mm hydrostatic head rating — the height of water column the fabric can withstand before leaking. Rating context:
- 1,500 mm = minimum "waterproof"
- 5,000 mm = waterproof for most rain
- 10,000 mm = waterproof for submersion (this product)
- 20,000 mm = fully waterproof for prolonged submersion
10,000 mm handles whitewater paddling, motorcycle touring in heavy rain, accidental submersion, and prolonged wet conditions.
Heavy-Duty 420D Ripstop Nylon
The pack is built from heavy-duty 420D ripstop nylon — much heavier and more durable than the 15D/20D fabrics used in sleeping bags and pillows. The ripstop weave prevents small tears from propagating. Triple-coated base for additional abrasion resistance.
Hypalon Non-Wicking Roll-Top Closure (NEW)
The pack closes with a hypalon non-wicking roll-top:
- Hypalon = a synthetic rubber (chlorosulfonated polyethylene) used in high-performance waterproof applications. UV-resistant, chemically stable, and durable.
- Non-wicking = the fabric doesn't absorb water via capillary action, so the closure stays dry even when wet.
- Roll-top = fold the top down 3-4 times and clip with the buckle. Folding creates a mechanical seal that's reliable even if water gets past the buckle.
Patented Field Repair Buckles (NEW — KEY FEATURE)
The buckles are STS's patented Field Repair Buckles — replaceable in seconds with just a Phillips screwdriver (no special tools, no sewing). Per STS: "the Field Repair Buckles can be replaced in seconds with just a Phillips screwdriver." A broken buckle doesn't end a trip — swap it out roadside/trail-side in minutes. Same buckle system used on STS dry sacks and the Air Chair.
White Interior TPU Laminate
The interior is lined with a white TPU laminate that reflects light — makes gear inside the pack much easier to find in low-light conditions (early morning, dusk, kayak cockpit, dark tent). Practical feature for paddlers and motorcyclists who often access gear in dim conditions.
Ovalised Shape (NEW — DESIGN RATIONALE)
The pack has an oval cross-section rather than round. Benefits:
- Easy stacking — packs nest together for transport/storage
- Secure lashing — lash rails run along the long axis, providing multiple attachment points
- Comfortable carry — the flat back panel sits closer to the wearer's spine, distributing weight better than a round pack
Grab + Lash System (NEW — ATTACHMENT)
The pack has both a grab handle and lash rails — strong and versatile attachment points for:
- Securing to kayaks (deck rigging)
- Attaching to bikes (handlebar/frame bags)
- Motorbike luggage (rack straps)
- Rooftop cargo boxes (tie-down points)
- Carrying multiple packs together
Adjustable EVA Foam Harness
The pack harness uses adjustable EVA foam — closed-cell foam that's lightweight, doesn't absorb water, and provides cushioning. Combined with the sternum strap and removable 38mm webbing hipbelt (waist strap), the harness holds the pack firmly during active use.
Sizing & Use Cases
30L / 50L / 75L Sizes
Three sizes for different trip lengths:
- 30L — day trips, wet-weather commuting, short paddles
- 50L — weekend trips, 2-3 day paddles, multi-day motorcycle trips
- 75L — week-long expeditions, full gear loads for extended paddles or motorcycle touring
Load Capacity (PER STS FAQ)
Per STS FAQ: "A short distance carry limit might be 20Kg, a longer distance carry limit would be 12Kg, depending on the wearer." Load capacity depends on trip length and user strength:
- Short distance (car to campsite, portage): up to 20 kg
- Longer distance (multi-day carry, all-day hike-in): up to 12 kg
The waist strap (NOT a hipbelt per STS FAQ) helps distribute weight but isn't a true load-bearing hipbelt.
No Inside Pockets (PER STS FAQ)
Per STS FAQ: "It doesn't [have inside pockets] - but packing smaller items in dry bags/stuff sacks will keep them easy to find inside the pack." The Big River is intentionally minimalist inside — pack smaller items in dry bags or stuff sacks to organize and protect them.
Non-Adjustable Harness (PER STS FAQ)
Per STS FAQ: "A non-adjustable harness was chosen for durable simplicity on complex days of hauling gear." The harness is intentionally non-adjustable — trade-off between adjustability and durability. For multiple wearers sharing the pack, this is a limitation.
Sustainability & Repair
Non-PFAS Laminate
The waterproof laminate is non-PFAS — uses chemistry that doesn't contain PFAS ("forever chemicals"). This is becoming a standard expectation from outdoor brands, and STS is ahead on this.
STS Warranty Service
STS offers warranty service on the Big River Dry Backpack — for manufacturing defects, premature wear, or unexpected failures. STS is known for responsive warranty service (verified by multiple customer reviews of other STS products).
Best Use
Activity
Paddle Sports (kayaking, canoeing, rafting), Motorcycle Touring, Wet-Weather Commuting, Alpine Adventures, Canoe Expeditions
Materials & Construction
Fabric
100% Nylon (420D ripstop, heavy-duty, triple-coated base, non-PFAS laminate)
Hydrostatic Head
10,000 mm (fully waterproof for submersion and prolonged wet conditions)
Closure
Hypalon non-wicking roll-top with Field Repair Buckles
Interior
White TPU laminate (reflects light for gear visibility)
Seam Construction
Double-stitched, fully taped waterproof seams
Shape
Oval cross-section (for stacking + lashing)
Dimensions & Weight (by size)
| Measurement | 30L | 50L | 75L |
|---|---|---|---|
| Weight | 23.6 oz / 670 g | 26.8 oz / 760 g | 28.9 oz / 820 g |
| Dimensions | 9 × 11 × 22 in 23 × 28 × 56 cm |
11 × 14 × 24 in 28 × 36 × 61 cm |
14 × 13 × 27 in 33 × 36.5 × 67.5 cm |
Performance (STS scales)
Weight Class
Heavyweight (purpose-built for rugged use, not ultralight)
Usage Class
Rugged Storage (the heaviest-duty tier on STS scale)
Harness & Carry System
Harness
Adjustable EVA foam (non-adjustable height per STS FAQ)
Sternum Strap
Yes (included)
Hipbelt
Removable 38mm webbing waist strap (NOT a load-bearing hipbelt per STS FAQ)
Grab Handle
Yes (top of pack)
Load Capacity
20 kg short distance / 12 kg long distance
Attachment
Lash Rails
Yes (along long axis — for attaching to kayaks, bikes, motorbikes, roofracks)
Inside Pockets
None (pack items in dry bags/stuff sacks for organization)
Profile
Brand
Sea to Summit (Australian outdoor gear, founded 1994)
Category
Dry Backpack / Waterproof Backpack / Paddle Sports Pack
Activity
Paddle sports, motorcycle touring, wet-weather commuting, canoe expeditions, alpine adventures
Season
Year-round (all seasons — handles all weather conditions)
Cleaning
Rinse with fresh water after exposure to salt, mud, sand, or dirt. For tougher grime, use a mild soap and a soft brush. Avoid harsh detergents that can degrade the waterproof laminate. Air dry completely before long-term storage. Do not machine wash or tumble dry — can damage the seam sealing, TPU interior laminate, and Field Repair Buckles.
Drying
Open fully and hang or stand in a well-ventilated area. The 420D nylon dries relatively slowly due to its thickness — air-drying takes longer than 15D/20D fabrics. For long-term storage, ensure the pack is completely dry before storage to prevent mildew and odor.
Roll-Top Closure Care
Periodically inspect the hypalon roll-top for cracks, cuts, or stiffness. Hypalon is durable but can degrade with years of UV exposure. To maintain water resistance:
- Roll the top down at least 3-4 times (more for submersion applications)
- Ensure the buckles are fully clipped and tensioned
- Clean the buckle tracks of any debris or salt
- Inspect the fold area for wear or pinholes
Field Repair Buckle Replacement (NEW)
Per STS description: "the Field Repair Buckles can be replaced in seconds with just a Phillips screwdriver." STS sells replacement Field Repair Buckles separately. To replace:
- Use a Phillips screwdriver to remove the screw/pin on the buckle
- Slide the old buckle off the webbing
- Slide the new buckle onto the webbing
- Re-insert the screw/pin and tighten
No special tools, no sewing. Carry a spare set of buckles on extended trips for emergency repairs.
Seam Sealing Inspection
The Big River uses double-stitched, fully taped waterproof seams. Periodically inspect the seams for:
- Peeling or delaminating seam tape
- Stitching failures (broken threads)
- Punctures or cuts near seams
If a seam starts to fail, repair with STS seam sealer or contact STS warranty service.
Lash Rail Inspection
<The lash rails (along the long axis) are attachment points — inspect periodically for wear, especially if you strap the pack to motorbikes or roof racks frequently. STS sells replacement lash rails if needed.
Harness Webbing Care
The EVA foam harness and webbing straps can accumulate salt, dirt, and body oils. Periodically rinse with fresh water and a mild soap. Inspect the stitching on the harness attachment points for wear — these are the highest-stress areas of the pack.
Puncture Repair
Small punctures or cuts in the 420D nylon fabric can be repaired with STS repair patches or any heavy-duty silicone/PU repair tape. Clean and dry the area, apply the patch, and allow to cure for 12–24 hours before use. Larger tears or seam failures may need professional repair — contact STS warranty service.
Long-Term Storage
Store dry, clean, loosely folded, and out of direct sunlight. UV degrades the 420D nylon and the hypalon roll-top over time. For very long-term storage, consider stuffing with newspaper or rags to maintain shape and absorb any residual moisture.
Activity-Specific Tips
- Paddle sports: Always roll the top at least 4 times before getting in the kayak/boat. The 10,000 mm waterproof rating handles splash and brief submersion; the roll-top closure is the primary defense.
- Motorcycle touring: Use the lash rails to secure to the bike's luggage rack. The 420D fabric handles highway vibration and weather exposure well.
- Wet-weather commuting: The white interior laminate helps find gear in dark commute conditions. Pack electronics in separate dry bags inside the Big River for extra protection.
- Multi-day canoe expeditions: Pack smaller items in dry bags/stuff sacks inside the Big River for organization. Use the 75L size for week-long trips.
Shipping Policy
Components:
All component items (wheels, drivetrains, suspension, brakes, etc.) ship within 2-5 business days of purchase.
Bicycles:
Complete bikes typically ship within 2–3 weeks due to build, tuning, and inspection times. You will receive tracking information as soon as your order is ready to ship.
Riding Gear & Apparel:
Riding gear and apparel orders (helmets, jerseys, gloves, etc.) ship within 2-5 business days.
Returns & Exchanges:
If you received the wrong size or wish to exchange an item, it must be returned in original condition—unused, uninstalled, and with all packaging intact.
For full details, please see our Refund Policy before initiating a return.
