Elimination of bubble pulses has been the main concern of air gun users for the past years. Until now, the proposed solutions: divided chambers, spheres, have resulted in an appreciable loss of acoustic energy. The Casios-Simplon Water Gun, developed by CNEXO and SODERA, solved this problem using surprisingly simple means, which not only eliminate the disturbing secondary effects (bubbles) but greatly increase the acoustic efficiency of the air gun. The system uses the air gun as a pneumatic accelerator and creates the acoustic pulse by implosion. The emitted signal is free of disturbing secondary effects and its power spectrum closely approaches the spectrum of dynamite type sources. [NOT CONTROLLED OCR]