Osprey Ultralight Dry Stuff Pack Review: A Day Pack That Doubles as a Dry Bag

Introduction

Most packable day packs force a compromise: they are light and small when packed, but the moment weather turns, everything inside gets soaked. The Osprey Ultralight Dry Stuff Pack takes a different approach by building a waterproof dry bag first and sewing a backpack onto the back of it. The result is a 20-liter roll-top pack that weighs about seven ounces, packs down into its own pocket, and shrugs off spray, rain, and rough handling.

It was bought specifically for a trip to the Galapagos, where a bag needed to work as a daily day pack and a dry bag at the same time, surviving being thrown around on boats all day. That is a genuinely demanding brief, and this bag handled it well.

Who This Product Is For

This is a bag for travelers and outdoor users who want one item doing two jobs. If you are heading somewhere with boats, surf, heavy rain, or humid conditions, the waterproofing is the whole point. It also suits anyone with limited luggage space, since the entire pack stuffs into a small sewn-in pocket inside the main compartment and slides easily into a carry-on.

It is less suited to commuters or anyone carrying heavy electronics daily, for reasons covered below.

Main Strengths

The core design is simple: a 20-liter sack made from very thin ripstop nylon, with all seams sealed for waterproofing. The hardware choices stand out for a bag this light. Osprey uses lightweight but durable nylon YKK buckles throughout, and the front pocket gets a water-resistant YKK AquaGuard number 5 zipper. The roll-top closure is what pushes it into true dry bag territory, essentially making this a waterproof dry bag with a backpack sewn onto the back.

Capacity checks out. A reverse packing test filling the bag with 20 liters of packing peanuts confirmed the listed 20-liter figure is fairly accurate, though the usable space shifts slightly depending on how tightly you roll the top down. Three rolls is a pretty standard roll, and the side buckle lets you cinch everything down for a much smoother look than clipping the ends together like a traditional dry bag.

Packed size is arguably the best feature. The whole bag inverts into a pocket sewn inside the main compartment, and while it takes a little working to stuff it all the way back in, the result is remarkably small and light: roughly 200 grams total. For a bag that also functions as a dry bag, that packed footprint is genuinely hard to beat.

The external layout stays minimal, which is appropriate for a bag this simple. There is one front pocket, not very wide but surprisingly deep and large, plus two side water bottle pockets made from stretchy fabric. Those side pockets are generous for such a small pack: they expanded to hold a 16-ounce water bottle easily, while a one-liter bottle fits as well, with a compression strap on top to keep everything tight or attach something taller.

The carry system is about as comfortable as you can expect from a seven-ounce pack. Shoulder straps use two layers of mesh webbing, thinner mesh on the front and slightly thicker, softer mesh against the back, with an adjustable sternum strap that slides on a sewn-in piece of webbing.

Things to Consider Before Buying

The biggest trade-off is structure. There is no frame sheet and no back padding, so how the bag sits against your back depends almost entirely on what you put in it and how you pack it.

The front pocket, despite its AquaGuard zipper and a small drainage flap, is not as waterproof as the main roll-top compartment. Treat it as water-resistant storage for items that can tolerate some moisture rather than fully protected gear.

Comfort also scales directly with load. This is not a bag to pack fully loaded with heavy electronics and carry around all day; it will not stay comfortable when heavy. For a typical day-load of water, a towel, snacks, and a few soft items, it carried well for its weight class.

Buying Advice

If your use case matches the Galapagos-style scenario, wet environments, boat days, and minimal packed size, this bag is an easy recommendation. During that trip it proved lightweight, genuinely waterproof, large enough for a full day’s needs, and durable enough to survive being thrown around on boats.

It was not the only option considered. The Matador FreeRain 22 is almost identical in concept and would have been another strong choice for the same trip. The Osprey won out for two practical reasons: the chance to test a new pack, and the fact that it comes in about 40 percent lighter than the FreeRain 22. If minimizing weight matters to you, that difference is worth factoring in.

When packing, remember the structure trick: place bulky soft items like a towel or a small pack against the back panel to create a makeshift frame, then put larger, harder, rounder items in front of them. Packed that way, the bag carries far better than its seven-ounce spec suggests.

Conclusion

The Osprey Ultralight Dry Stuff Pack is a simple, functional day pack that also works as a genuine dry bag. It offers enough capacity for a full day out, carries decently for such a small and light bag, and packs down small enough to live in any carry-on. The lack of structure is the main compromise, meaning comfort and shape depend on how thoughtfully you load it. For travelers who want waterproof security and near-zero packed bulk in one item, it is one of the most sensible packable day packs available.