If you're going hiking, this is a suitable backpack. The material of choice for this bag is nylon and it has a volume of 68 litres.
From Amazon
Osprey Kyte 68l Woman Backpack M-L
The product is available from £173.12 at international stores.
OnBuy
Osprey Kyte 68 Womens Backpacking Backpack Black WM/L