Submarining is an injury-causing phenomenon in which the pelvis and hips slip out from under the lap safety belt restraint. Serious or fatal injury of the abdominal contents, the lower dorsal and the lumbar spine and the diaphragm may occur because of intrusion of the lap belt into the abdomen after sliding off the bony pelvis.
Race car constructors recognize the improved control of the pelvis and hips provided by seats with little or no padding and with stiff elevations in front of the buttocks. Only one manufacturer has incorporated similar design into production car seats. Such designs promise to reduce the risk of submarining and to improve lap safety belt function.