Experiments have been performed to investigate the simulation of cavitation bubbles by the implosion of thin‐walled glass spheres underwater. The bulbs were evacuated suitably gas‐filled if necessary, sealed, and then fractured underwater. High‐speed photography was used to study the implosion process and the radiated pressure waves were sensed by a hydrophone. The photographs revealed that the mode of collapse depended on the nature of the fracturing process. With a small impact, the glass is only punctured locally, and the glass appears to be fractured effectively by the inrushing water, giving rise to an unsymmetrical breaking. A more symmetrical fracture is obtained by using an externally generated shock wave. The possible buffering effect on the implosion of containing gas at appreciable pressure in a glass bulb was also investigated, together with the substitution of the surrounding water with a more viscous liquid. This type of experiment permits the variation and control of a number of parameters in the implosion phenomenon.