Abstract: Bag (1) comprising a first layer (2) and a second layer (3) of a material, wherein the first layer (2) and the second layer (3) is merged at several of their edge areas (10a, 10b, 10c) thereby forming a compartment (11). The first layer (2) and the second layer (3) comprise an additional edge area (10d) which forms an opening (12) into the compartment (11). The bag (1) comprises a closing device (20) comprising a tightening element (21) provided in a channel (22) transverse to the bag (1) close to the opening (12). A first end (21a) of the tightening element (21) projects from the channel in an initial state. The closing device comprises a stopping device (23) provided inside the channel in the initial position. The stopping device, when pulled out of the channel in the closed state, prevents the tightening device from moving back into the channel.