Diving and pneumothorax cannot go together. An air bubble between the visceral and the parietal pleura will change its size according to Boyle's law, and pneumothorax might increase in size during the ascent from a dive. We would like to present the case of a professional diver, who was engaged in active diving for a period of five months during which time he made 80 to 85 dives with pneumothorax. As far as we know, this is the first such case published in the medical literature. We should also like to emphasize the protracted nature of the pneumothorax, which persisted for that time without changing size. This diver had no medical problems with diving, and the deeper he descended, the better he felt. No tension pneumothorax ever occurred and the diagnosis was made by chance.