The purpose of this program is to develop and prove out a theoretical method for accurately predicting the critical buckling strength of externally pressurized cylinders made from ortho tropic materials and to find the optimum construction of filament reinforced plastic (FRP) cylinders under such loading. A description of the program and its significance to the overall BuShips Deep Submergence program and a summary of the work accomplished to date are given. Theoretical analytical expressions for predicting elastic buckling collapse and elastic constants of FRP cylinders are presented and discussed. Results of initial buckling and discontinuity stress analysis of proposed test cylinders are presented.