I recommend the backpack bag by Under Armour. It is water proof, has a mesh lining that rests on your back, so it is breathable and the best part is that the straps that go on your shoulders are foamy so they don't dig into your shoulders. Best bag ever, it was $20 at Dicks, so you would be able to find it there or any other place like that. We have navy one and a black one. I've seen a grey one and I think that I've seen pink and a light blue also. There is also a little zipper part in the front for your easy access stuff.