A dry bag is cheap insurance against the single most common way backpacking gear gets ruined: water. Whether it’s a surprise downpour, a river crossing, or just a canoe trip, the right dry bag keeps your sleep system, electronics, or entire pack contents bone dry. Here’s what’s worth carrying.
The standard pack-liner size and weight-to-durability ratio — line your pack with one instead of relying on a rain cover, and everything inside stays dry no matter how the water gets in.
Check Price on Amazon →Roll-Top vs Zip-Seal
Roll-top bags (fold-and-clip closure) are the standard for backpacking and paddling — lighter, cheaper, and fully reliable once you learn the technique (roll the top down at least 3 full turns before clipping the buckle). This is the right choice for a pack liner or any bag you seal once and don’t need to open repeatedly through the day.
Zip-seal bags (welded waterproof zippers) open and close faster, which matters for a daypack or camera bag you’re accessing constantly — but they cost more, weigh more, and the zipper is one more failure point to eventually replace. Reserve these for frequent-access use cases, not as your main pack liner.
Sizing by Use Case
| Size | Best For |
|---|---|
| 2-5L | Phone, wallet, keys, small electronics on a river crossing or canoe trip |
| 8-13L | A single layer, sleeping bag, or camera setup |
| 20-35L | Full pack liner — the size most backpackers actually need |
| 40L+ | Canoe/kayak trip gear haul, or car camping overflow |
Most backpackers only need one bag: a 20-30L liner that lines the inside of the main pack compartment. Smaller bags are worth adding only for genuinely water-sensitive items (phone, camera, first-aid kit) you want double protection on.
Our Top Picks
| Dry Bag | Size | Weight | Price | Best For | Buy |
|---|---|---|---|---|---|
| Sea to Summit Lightweight Dry Sack | 20L | 2.1 oz | ~$30 | Best pack liner | Amazon |
| Sea to Summit eVent Compression Dry Sack | 20L | 5.6 oz | ~$65 | Compresses your sleep system too | Amazon |
| Earth Pak Dry Bag | 10L / 20L / 40L | Varies | ~$25-35 | Best budget | Amazon |
| Osprey Ultralight Dry Sack | 6L / 12L / 20L | 1-2 oz | ~$20-30 | Lightest roll-top line | Amazon |
| NRS Bill’s Bag | 55L+ | Heavy | ~$100+ | Canoe/kayak/rafting gear haul | Amazon |
| YETI Panga | 50L / 75L | Heavy | ~$300 | Submersible, expedition-grade | Amazon |
1. Sea to Summit Lightweight Dry Sack — Best Pack Liner
Size: 20L | Weight: 2.1 oz | Price: ~$30
This is the bag most backpackers should actually buy: light enough to disappear in your pack weight, tough enough (70D siliconized nylon) to survive years of daily use, and sized right to line a typical 40-60L backpack. Use it instead of a rain cover — line the inside of your pack with it, load your gear inside, and roll the top before closing your pack. Rain, stream splashes, and submersion during a crossing all become non-issues.
2. Sea to Summit eVent Compression Dry Sack — Best Dual-Purpose
Size: 20L | Weight: 5.6 oz | Price: ~$65
This one does double duty — waterproof like a standard dry bag, but with compression straps that also shrink your sleeping bag or clothing layer down smaller, and an eVent fabric panel that lets air (not water) escape as you compress. Heavier and pricier than a basic roll-top, but genuinely useful if you want your dry bag to also solve a packed-size problem.
3. Earth Pak Dry Bag — Best Budget
Size: 10L / 20L / 40L | Price: ~$25-35
A genuinely capable roll-top dry bag at a fraction of the premium-brand price, with a wide size range and included accessories (phone case, compression straps on some sizes) that usually cost extra elsewhere. Not as refined as Sea to Summit, but reliably waterproof and a smart pick for budget-conscious backpackers or outfitting a family for canoe trips.
4. Osprey Ultralight Dry Sack — Lightest Roll-Top Line
Size: 6L / 12L / 20L | Weight: 1-2 oz | Price: ~$20-30
Osprey’s ultralight line shaves weight further than most competitors while staying genuinely waterproof for standard use (rain, splashes, brief submersion) — a smart pick for ounce-counters who still want a full size range from small electronics bags up to a pack liner.
5. NRS Bill’s Bag — Best for Canoe/Kayak/Rafting
Size: 55L+ | Price: ~$100+
Built specifically for paddlesports, with a heavier-duty fabric and roll-top closure rated for real submersion, not just rain and splashes. Overkill for backpacking, but the right choice if you’re hauling a full camp kit down a river and need genuine confidence it’ll survive a flip.
6. YETI Panga — Submersible, Expedition-Grade
Size: 50L / 75L | Price: ~$300
The heaviest-duty option here — fully submersible, abrasion-resistant, and built to the same standard as YETI’s coolers. Genuinely excessive for typical backpacking, but the right call for expedition use, commercial rafting, or anyone who wants zero doubt about their gear staying dry in serious conditions.
Which Should You Buy?
- Most backpackers: Sea to Summit Lightweight Dry Sack, 20L, as a pack liner — skip the rain cover entirely.
- Want compression too: Sea to Summit eVent Compression Dry Sack.
- Budget-conscious or outfitting a family: Earth Pak.
- Ounce-counters: Osprey Ultralight.
- Canoe/kayak/rafting: NRS Bill’s Bag or, for serious expedition use, the YETI Panga.
Related Guides
- 📚 Ultralight Backpacking Gear Guide — the complete guide
- How to Keep Your Gear Dry in the Rain
- Backpacking Gear Checklist
- Best Backpack Coolers
Carry less. Hike farther.
Frequently Asked Questions
What size dry bag do I need for backpacking?
Do I need a dry bag if I already have a rain cover for my backpack?
What's the difference between roll-top and zip-seal dry bags?
Get the Sub-10 lb Ultralight Gear Checklist
Join the free PackLite Life newsletter — new gear guides, trip reports, and trail-tested tips — and grab the printable checklist when you sign up. No spam, unsubscribe anytime.