The present invention is directed to an apparatus and method for counteracting and defeating underwater threats posed to surface ships, submarines, marine facilities and underwater installations, specifically, those threats posed by objects such as torpedoes, underwater mines, explosives and hostile demolition personnel.  In particular, the invention relates to an apparatus and method for generating high pressure shock waves that are capable of disabling or destroying underwater threats. 
Marine assets are critical in maintaining both a viable military defense and a viable national economy.  The ability to safely station and maneuver surface ships and submarines within a threat environment is critical to the success of a naval component of a national defense program.  Similarly, marine facilities such as ports, underwater communication lines, drilling rigs and underwater pipelines are crucial to maintaining a viable national economy.  Surface ships, submarines, ports and underwater installations, however, are susceptible to a variety of marine weapon systems including torpedoes, underwater mines, and explosives as well as hostile underwater demolition personnel.  Thus, the protection of these assets is critical with respect to both military and economic defense programs. 
A conventional method of countering a marine attack is to detect the presence of an incoming threat in sufficient time to launch a counter attack, and then to respond in kind with conventional weapons in an attempt to destroy the incoming threat.  Although various conventional counter measure weapons may be employed, such counter measure weapons generally rely on conventional explosive ordinance that must be carried by the very ships that must be defended.  The amount of ordinance that can be carried for the purpose of self-defense on a ship is limited, however, thereby necessitating a trade off between the offensive ability of a ship versus the ship's own self-defense capability.  Further, conventional counter measure weapons require sophisticated firing control mechanisms to enable rapid target acquisition, and—given the limited amount of reaction time available after threat detection—such systems are necessarily susceptible to targeting errors that could prove detrimental or even fatal.  Finally, the use of conventional explosives limits the possibility of a defense system that periodically fires to prevent infiltration, which would eliminate the need for sophisticated detection technology.  For example, it is not practical to have large periodic conventional explosions occurring in a commercial port.  Accordingly, conventional explosive ordinance defense systems are fired only when an actual threat has been detected, which in some cases may be too late for an effective response. 
In view of the above, it would be desirable to provide an apparatus and method for counteracting and defeating underwater threats posed to surface ships and submarines without require the use of conventional explosives.  It would further be desirable to provide an apparatus and method for defeating underwater threats that would allow for systematic and periodic firing to prevent infiltration of a marine threat.