I've been using this style of dry pack for both personal trips and professional guiding for seven seasons. It has a roll-top closure, secured with buckles and straps. This waterproof dry bag comes equipped with backpack style shoulder straps and a waist belt to aid in portaging.
The 70L size is perfect for a solo paddler who packs heavy (or carries extra for guiding) or for a duo who can pack conservatively.
The monstrous 115L dry pack holds a serious load! This is ideal for a small family or group.