Gastric perforation secondary to barotrauma is rare. The case of a diver suffering from gastric rupture due to a decompression accident is presented here. This rupture was a linear one, localized on the lesser curvature and responsible for a large pneumoperitoneum. Rupture occurs with an excluded stomach, a condition implying cardio-pyloric occlusion. The expansion of intra-gastric air, further worsened by accelerated surfacing provokes excessive gastric dilatation leading to partial or complete rupture (by virtue of the Boyle-Mariotte law: Pressure x Volume = constant). The lesion is always on the lesser curvature. However, it is often difficult to locate, even when peroperative gastroscopy is performed.