The 100% Waterproof Backpack from Aqua-Quest comes in various sizes and colors.
The drybag depicted in the image on the left is the Aqua-Quest 100 percent waterproof backpack. The volume is 30L or 1800 cubic inches. They call this one “The Sport”, Charcoal Model. The logo is reflective for night time safety. Multiple water bottle storage pouches, and the whole bag is engineered for high end durability.
You can also get a version that is half the size. It is a waterproof Aqua-Quest drybag backpack that is 10L or 600 cubic inches in volume. More waterproof backpacks are available other than this one.
More Waterproof Backpack options
This one is called the Outlander packable handy lightweight travel backpack day pack.
Obviously, you can see this is the blue version that they call mariner blue. However, you can get this exact same bag in 7 different color schemes.
This is made from waterproof nylon material, and also features mesh breathable straps. Read more about this waterproof backpack and all of it's features by clicking the image of this bag here.
You will also be able to read through a huge number of customer review comments. In fact, the main reason I selected this one out of the bunch was due to the very high number of positive reviews and ratings for this particular water proof bag.
They call this one the OverBoard waterproof pro sport backpack. This is the red version, but it also comes in blue, yellow, and black. It has a 20 liter capacity in general. It has the standard straps for wearing on your back, as well as a top handle for carrying that way if you want.
Click the image of the waterproof backpack seen here for a lot more camera angles and product specifications.