Abstract: Bag for use by divers for transporting articles under water, including valves for controlling the buoyancy of the bag under water. An essential consideration is that this transportation shall take place while the articles are kept dry, for example tools or materials to be used in diver operations. According to the invention a receptacle (10) for articles to be transported, constitutes a buoyancy chamber, and is provided with at least one unidirectional valve (15, 16, 18) for buoyancy control, as well as a watertight closure, preferably a zipper (4) for an opening to the receptacle (10).