If you're going hiking, this is a suitable backpack. One of the materials used to make this bag is polyester and things you want to keep extra track of can go in the inner pocket.
From Amazon
Vaude Brenta 24 Backpack 20-29L - Blue, One Size
Trekkinn
Vaude Tents Brenta 24l Backpack Blue,Grey
Hardloop
Vaude Brenta 24 - Hiking backpack Blue 24 L