As long as shipping existed ships were exposed to the hostile environment and shipbuilders from the oldest times learned that in order to survive in this environment ships had to stable. They developed also by the method of trials and errors the practical knowledge how to build comparatively stable ships, however hot stable enough to ensure the safe completion of the voyage. In modern times understanding of basic laws of ship's geometry and static stability enabled naval architects to make calculations during the design stage, then developments in ship hydrodynamics allowed to calculate the behaviour of ship in a seaway and the effect of external forces on stability. Nevertheless from time to time ships were lost as a result of capsizing quite often with all hands onboard. Even introduction by some nations of stability regulations which also included certain stability criteria did not eliminate casualties. For more than twenty years IMO have made numerous attempts to establish international requirements for ship stability. The achieving of this aim is now becoming possible because of the latest development of stability criteria, which is one of the most complex problems of ship design and construction.