Sea to Summit
Sea to Summit Big River Dry Bag (20 L)
- Waterproof build: 6/10 How well its build keeps water out, from the published seams, closure and submersion claim.
- Weight for its size: 2/10 How much it adds to your pack for the space it protects.
Rough use on the outside of a pack or in a boat, where a thick fabric matters more than weight
- Capacity
- 20 L
- Weight
- 250 g
- Seams
- Taped
- Closure
- Roll top
- Fabric
- 420 denier
Where to buy
Tamarack Outdoors £38.40 In stock. Delivery £3.49. Dull Gold colour shown. Free delivery over £50.
View at shop: Tamarack OutdoorsSea to Summit £48 In stock. Delivery £4.50. 20 L in stock except Jet Black. Free delivery over £75.
View at shop: Sea to SummitPrices checked 8 Nov 2026 on each shop's own page; shops can change them. We earn no commission on these links; shops are listed by price. More
Our ratings (out of 10)
1 to 10, compared with the whole market. Each says what it's based on. How we score
Waterproof build
From maker's figures 6/10How well its build keeps water out, from the published seams, closure and submersion claim. 6: A bit better than average.
Double-stitched, tape-sealed seams and a hypalon roll-top. The 420D fabric has a 10,000 mm hydrostatic head, but Sea to Summit's FAQ says to avoid submersion and gives no submersion claim: the 3 band.
Weight for its size
From maker's figures 2/10How much it adds to your pack for the space it protects. 2: A weak point.
250 g for 20 L is 12.5 g/L, in the 12.0+ g/L band (Sea to Summit's figure).
In short
Good for
- Rough use on the outside of a pack or in a boat, where a thick fabric matters more than weight
- Wet trips with kit that must stay dry: tape-sealed seams and a 10,000 mm fabric
- Not for being under water: no submersion claim
Strengths
- Tough 420D nylon with a TPU laminate
- 10,000 mm hydrostatic head
- Double-stitched, reinforced, tape-sealed seams
- Hypalon non-wicking roll-top with a replaceable Field Repair Buckle
- Sizes from 5 to 65 L
Weaknesses
- 250 g for 20 L (12.5 g/L), about four times the weight of a 20 L Ultra-Sil dry bag (58 g)
- No submersion claim
- No independent reviews of the 20 L were found, so durability and ease scores are missing
Sources
We haven't tested this ourselves. Every score comes from these specs, tests and reviews.