In this contribution we report on modeling underwater explosion in the framework of molecular dynamics. We have developed a computer program which allows studying the underwater explosion in two dimensional Lennard - Jones liquid. Calculations of the dynamical structure of underwater explosion displayed the striking resemblance of the underwater-explosion evolution obtained and the real process; namely, generation of a shock wave and its expanding; formation of a cavity; disintegrating the shock wave, when reaching a surface, into two parts which begin to move in opposite direction parallel to the surface; transforming the cavity into a water crater of an arising water volcano; its activity and decay.