I used it for about 25 consecutive days. It is indeed waterproof, especially if you make 2-3 rotations of the wings. It is durable with a useful external pouch with a waterproof zipper (it can fit flat items, such as money, keys without a keychain, credit card, etc.). The 30 liters is a medium solution. It is not bulky or heavy, but it can definitely fit a towel, a small pharmacy, food, 2-3 clothes, and even a pair of shoes (at the bottom). Excellent value for money (22€)