A bag includes a body portion defining a pouch having an open end and a strengthening rib. A strap of the bag has a first end connected to the body portion adjacent a first side of the open end, and a locking mechanism is connected to the body portion adjacent a second side of the open end. The locking mechanism is arranged to releasably engage a second end of the strap such that the bag can be connected to immovable objects to prevent theft of the bag. Further, a closing mechanism is disposed on the body portion and arranged to close the open end. The closing mechanism has a moveable head that is arranged to engage the second end of the strap when the strap is engaged with the locking mechanism, such that unauthorized access to the contents of the open end is prevented when the bag is locked.