25 litres is about as large a pack as we would like to wear when on a bikepacking trip, even then keeping it for the light but bulky items that won't lead to sore backs over time. With that in mind we were very interested to take delivery of this waterproof, roll top rucksack from Aquapac.
It breaks a few waterproof bag rules here - and all for the better. For one it isn't just a single huge compartment as most are, instead being split using a handy waterproof bag inside. Held in place, and removable, by zip we used it to separate our dirty from clean kit, or wet from dry, when on the move and for that it was invaluable. Let's face it, you are never going to be able to keep all your kit dry on a trip, and this prevented contamination of our valuable dry kit when packed in together with damp jackets or towels. We also found the external mesh pockets very useful to pack wet gear that could potentially dry through the day, also keeping it out of that precious dry space - another feature rarely seen on waterproof packs.
The semi-rigid back was comfortable and just stiff enough to prevent sharp items poking through and causing discomfort - they say it is removable to use as a seat, but we didn't make a habit of it - and the harness system was perfectly comfortable even over long rides.
The side clipping waist strap was harder than the usual meet-in-the-middle style, requiring a bit of reaching around to get it clipped, but that was a small complaint about an otherwise excellent pack.