A WAXED BACKPACK
It's waxed so it's waterproof. It's a backpack so you can carry it on your back.
Specs about the bag from the Stone and Cloth site:
Specs: 17" x 11.5" x 4.25" / 13L
Our backpack is a great waterproof bag for school or the office. This waxed canvas bag is remarkably water-resistant and improves with age. Featuring antique brass zippers, it functions as a laptop backpack when the padded laptop sleeve is utilized.
*Products are made in limited batches from a sew shop in Los Angeles.