Abstract: A diving apparatus (10) supplies breathing air (L) and includes a basic body (12), a tank interface (20), a pressure reducer (22), a mouthpiece interface (24), and a display device (30). The tank interface connects to a breathing air tank (90) for the inlet of breathing air into the diving apparatus. The mouthpiece interface is configured for connection of a mouthpiece (92) for the supply of breathing air from the diving apparatus. The pressure reducer is arranged in a gas path of the diving apparatus between the tank interface and the mouthpiece interface for reducing gas pressure. The display device includes a display instrument (32) and a display line (34). A holding element (40) is configured to detachable fasten the display line at the basic body. A diving system (100) is provided including the diving apparatus (10), a breathing air tank (90) and/or with a mouthpiece (92).