5L dry bag: It is small in size, suitable for protecting small items such as wallets, keys, towels, glasses, and compasses. It is also very popular with children.
10L dry bag: It is a moderate size, suitable for short trips to pack small items. Suitable for protecting sweaters, toiletries, flashlights, mobile phones, notebooks, water bottles, etc.
20L dry bag: It is big enough to carry the items you need for a day trip. Suitable for protecting clothes, shoes, tablet PC, bath towels, binoculars, cameras, hand tools, food containers, etc.
30L dry bag backpack: It is suitable for traveling more than one day. Suitable for protecting more clothes, life-saving bags, parachute hammocks, ponchos, water containers, etc.
40L dry bag backpack: It provides gear protection for a trip that will last up to a week: two people's clothes, small sleeping bag, wetsuit, air mattress etc.
The dry bag is not specifically designed for diving, so do not submerge the bag fully under water for more than couple of seconds.