To deter people from looking through your stuff as you head out from the hostel on an outing, use nylon cable ties on your backpack.
They’re especially useful with top loading backpacks that have no zippers or a place to clamp a lock on.
Buy cable ties at any hardware store. They come in all sizes and colors and are a dime a dozen. If you can’t find them, then twist wires, the kind that come with bagged bread, can pull off some deterring effect for your stuff.
