This is the 2nd report on structural feasibility study of an underwater half drop shaped shell, the 1st one was reported in ISOPE'93. Dynamic characteristics of a large underwater shell of revolution are studied iii the paper. Large rotational shell having optimum shape with respect to the hydrostatic pressure can be used for a storage of LNG or vessel of super conducting coil for power storage in the future. In this study, which is one of many structural feasibility studies for the shell, vibration characteristics of the shell are examined using numerical analysis, in which finite elements for the structure and boundary elements for surrounding water are used. Natural frequencies and modes of an underwater drop shaped shell are examined using a developed numerical code "DASOR." The code was justified by comparison with other results of vibration analysis of a submerged cylindrical shell for various water levels. The added mass effect of the underwater drop shaped shell in each vibration mode is discussed and the ratio of modal mass of structure in water and in air in the lowest mode proved to be very large specially for axisymmetrical mode and horizontal lowest mode. A seismic response analysis of the underwater shell of revolution with the excitation coming from a horizontally moving seabed is performed numerically and statistically. The analysis using power spectrum density function provide with the responses of distribution of displacements, membrane stresses, and bending moments.