Here is a camera bag ready for harsh conditions. The Agua Stormproof Versa Backpack is IPX3 rated. It has a quick-draw mechanism that lets you grab your camera in 3 seconds. The backpack can be worn in 3 positions (regular, X, sling). The Agua Versa bag is snow, dirt, sand, and rain proof.
This bag can hold a DSLR and 2/3 lenses. It has a Tarpaulin, neoprene, Lycra, and polyester construction. Its impact-resistant bottom panel protects your gear.