The Large Dutch military holdall bag is ideal for camping or really any trip. The bag is made from a strong condura material, so you can trust it not too rip or tear easily. It also has a plastic bottom for extra protection from the ground.
I have had one for about 2 years now and I say it's one of the best investments I've ever made. It's durable, waterproof and quite large allowing you to carry a awful lot of stuff. My only complaint is the fact that because they are surplus they tend to be a bit worn - Mainly the waterproofing on the inside starts to flake off leaving it virtually non-waterproof.