The short version
- Dry bags are sized in liters. 5L holds phone, keys and snacks, 10L a jacket or small sleeping bag, 20L is the do-everything day size, and 30L+ is for overnight gear.
- "Waterproof" usually means it survives splashes and a quick dunk. Only bags rated "submersible" (often IP67: 1 m for 30 minutes) are built for extended time underwater.
- Roll the top down tightly at least three times, then buckle. Fewer rolls is the most common reason dry bags leak.
- Pack several smaller bags rather than one big one, and double-bag electronics.
- Store bags clean, completely dry and out of the sun. Keep bug spray and solvents away from them.
A dry bag is the simplest piece of watersports gear there is: a tough sack with a roll-down top. It's also the one people most often use wrong. They pick the wrong size, roll it twice, strap it fold-up to the deck and wonder why the car keys got soaked. This guide covers how to choose the right size and material, how to seal one properly, and what to pack for paddling, boating, beach days and overnight trips.
How dry bags work
A roll-top dry bag seals by folding the stiffened top band over on itself several times, then clipping the ends together. Each fold creates another barrier water has to get past. Most bags have a stiffening strip sewn into the top, so the first fold is crisp and the following ones lie flat.
The bag body is a waterproof coated fabric with welded or taped seams. The top closure is the weak point, so how well you roll it matters more than how expensive the bag was.
Waterproof vs submersible
Manufacturers use these words carefully. SealLine, one of the original dry-bag makers, defines three levels:
| Rating | What it handles | Good for |
|---|---|---|
| Splashproof | Light rain and splashes | Deck bags and stuff sacks that stay inside a hatch |
| Waterproof | Quick submersions | Paddling where you may tip or flip. This is what most roll-top dry bags are. |
| Submersible | 1 m of submersion for 30 minutes (the IP67 test) | Prolonged wet conditions: whitewater, swims, gear that may end up underwater |
If a bag is rated "waterproof" without a submersion rating, assume it's designed to survive a capsize and a quick recovery, not to sit on the bottom of a lake. For a deeper look at IP codes, see Waterproof Ratings Explained.
Choosing a size
Dry bags are measured by volume in liters. These are typical uses:
| Size | Fits | Best for |
|---|---|---|
| 1–3L | Phone, keys, wallet, car fob, lip balm | A small bag clipped inside a PFD pocket or SUP deck bungee |
| 5L | Valuables, snacks, sunscreen, a light layer | SUP and kayak day trips, snorkel boat rides |
| 10L | A packable jacket or fleece, a small sleeping bag, first aid kit | A spare-layers bag, kids' change of clothes |
| 20L | Full change of clothes, towel, lunch, layers | The most versatile size: day paddles, boat days, beach days |
| 30–40L | Sleeping bag and pad, or a weekend's clothing | Kayak camping, overnight canoe trips (often as a backpack or duffel) |
| 55L and up | Tent, sleeping system, a week of clothing | Expedition canoeing and rafting, boat lockers |
SealLine's rough guide matches this: 5L for a few meals or baselayers, 10L for a down jacket or small sleeping bag, 20L as the most versatile size, and 30L and up for most overnight gear. For pack-style bags, 20L suits a day trip, 30–40L a weekend, and 70L a long weekend.
Listed volumes usually describe the bag after it's properly rolled. Because you need at least three rolls, a bag packed full to the brim won't seal. Leave several inches of empty space at the top, or buy one size up.
How to seal a dry bag properly
- Pack it, leaving room at the top for rolling.
- Burp the air. Squeeze out excess air before you roll, so the bag packs flat in a hatch. On a SUP or for swimming, leave a little air in for buoyancy.
- Straighten the top band. Line up both sides of the stiffener so there are no wrinkles.
- Fold, don't twist, at least three times. NRS and SealLine both recommend a minimum of three tight, wrinkle-free folds. More is better.
- Buckle. Clip the ends together over the top, or clip each end to a side strap on bags designed for compression.
- Stow it fold-down or facing away from spray. NRS recommends placing the closure down or away from waves to protect the seal.
Never clip a dry bag to yourself in moving water or surf, where it could become an entanglement hazard. On paddleboards, secure bags under the deck bungees. In kayaks, tie them into the boat so they don't float away in a capsize.
Materials and features
| Material | Strengths | Trade-offs |
|---|---|---|
| Vinyl (PVC) coated | Economical, resists punctures, tears and mildew, stays flexible in the cold | Heavier. Less eco-friendly. |
| Polyurethane (PU/TPU) coated, PVC-free | Much more resistant to punctures and abrasion than vinyl. Lighter. Less environmental impact. | Costs more |
| Lightweight nylon (silnylon-style) | Very light and packable | Not for rough handling. Best inside another bag or hatch. |
Features worth paying for:
- Clear window or clear body: you can find things without unpacking.
- Purge valve: lets you squeeze out trapped air after sealing, which is great for compressing sleeping bags.
- Shoulder straps: turn a 20–40L bag into a backpack for portages and beach walks.
- D-rings and lash points: for securing the bag to a deck or frame.
- Bright color: easier to find if it goes overboard.
Shop the gear: Dry bags & storage · Waterproof phone pouches
What to pack: kits by activity
SUP or kayak day paddle (5L + 10L)
- 5L: phone (in a waterproof pouch inside the bag), keys, ID, cash or card, sunscreen, lip balm, energy bar
- 10L: windproof jacket, light fleece, hat, small first aid kit
- Water bottle clipped outside the bag
Boat or snorkel day (20L)
- Towel, dry shirt, sun hoodie, hat and sunglasses
- Snacks, sunscreen, seasickness medication if you need it
- Small bag of valuables inside the big bag
Kayak camping weekend (multiple bags)
- 20–30L for your sleeping bag (compress it with a purge valve if possible)
- 20L for clothing, divided into "camp dry" and "paddle wet"
- 10L for the kitchen kit, and 5L for electronics and the first aid kit
- Pack heavy bags low and centered in the hull for stability
Use different colors for different bags (red for first aid, blue for clothes, yellow for food) so anyone in the group can find things fast.
Protecting electronics
Phones, cameras and radios deserve two layers. Put them in a dedicated waterproof case or IPX7/IPX8-rated pouch, then put that inside a dry bag. A dry bag with a few drops of water inside is still "dry" by most standards, but those drops are enough to wreck a phone port. Some phone cases rated IPX7 protect contents in 1 m of water for up to 30 minutes when properly sealed. Read Waterproof Ratings Explained before trusting a phone's own rating at the beach.
Toss a small silica gel packet into your electronics bag to absorb condensation, especially on humid or cold days when moisture can condense inside a sealed bag.
Care and storage
- Rinse with fresh water after use, especially after saltwater, and air dry. Wash dirty bags with a soapy sponge.
- Keep insect repellents and solvents away from your bags. If they touch, wash the area thoroughly. Some repellents can damage coatings.
- Vinyl bags benefit from an occasional wipe with a vinyl protectant to stay supple. PU-coated bags don't need it.
- Store clean, completely dry and inside out, out of the sun. UV degrades coatings over time.
- Repair scuffs with a urethane repair adhesive, and patch holes with matching material and the right adhesive.
- Test before trips: fill with a little water, seal, and squeeze. Leaks show up fast.
FAQ
Are dry bags fully waterproof?
Most roll-top dry bags are designed to survive splashes and a quick submersion when rolled at least three times and buckled. For prolonged underwater exposure, choose a bag rated submersible, such as one tested to IP67 (1 m for 30 minutes).
What size dry bag do I need for paddleboarding?
For most day paddles, a 5L bag for valuables plus a 10L or 20L bag for layers and snacks works well. Secure them under the deck bungees.
Will a dry bag float?
A sealed dry bag with some air inside will usually float. Heavy contents or squeezing all the air out reduces that. Don't rely on it: tie bags to your craft so a capsize doesn't scatter your gear.
How many times should I roll a dry bag?
At least three tight, wrinkle-free folds, then buckle. NRS and SealLine both recommend three as the minimum, and more folds give a better seal.