A standard non-destructive testing probe (4) may be coupled with a localization system (10) according to the invention so as to determine the position of the apparatus (4) on the surface to be analyzed (1) at any moment.The localization system (10) comprises an ultrasonic emitter (12) and two ultrasonic receivers (14, 16) coupled with means for determining the distance between the emitter (12) and the receivers (14, 16), each of the components being able to be moved freely relative to each other. The coupling between the emitter (12) and the probe (4) allows the position of the latter to be determined by triangulation.A localization and mapping method is also described.