Hi there. I would like to buy my ds a decent quality backpack/rucksack (don't know the difference) for weekends when he goes on a little outing and needs to have a snack, water, pen and paper and maybe a gadget with him. I would like something that is not related to any movies, cartoons, books, etc, in fact, I would prefer it to look quite grown up. I would like it not to be too bulky so that he's happy to ride his bike or scooter with it on. A water bottle holder is a must. Any ideas anyone??