An experimental study on the underwater buckling of composite and metallic tubes is conducted to evaluate and compare their collapse mechanics. Experiments are performed in a pressure vessel designed to provide constant hydrostatic pressure through the collapse. Filament-wound carbon-fiber/epoxy, glass/polyester (PE) tubes, and aluminum tubes are studied to explore the effect of material type on the structural failure. Three-dimensional digital image correlation (DIC) technique is used to capture the full-field deformation and velocities during the implosion event. Local pressure fields generated by the implosion event are measured using dynamic pressure transducers to evaluate the strength of the emitted pressure pulse. The results show that glass/PE tubes release the weakest pressure pulse and carbon/epoxy tubes release the strongest upon collapse. In each case, the dominating mechanisms of failure control the amount of flow energy released.