In recent years, there has been an increased interest in the use of advanced composites in marine applications. It has been shown that by exploiting the inherent anisotropic nature of the material, fiber-reinforced composite structures can be tailored to allow automatic, passive, three-dimensional (3D) adaptive/morphing capabilities such that they outperform their rigid counterparts both hydrodynamically and structurally. Much of the current research on the shock response of composite structures focuses on air-backed structures with fixed-fixed or simply supported boundary conditions. Nevertheless, many critical components of marine structures where adaptive/morphing capabilities are needed are cantilevered-type structures, including propeller and turbine blades, hydrofoils, and rudders. This paper investigates the 3D transient response of cantilevered, anisotropic, composite marine structures, namely, fully submerged cantilevered plates, subject to a range of shock loads. Structural responses and the initial failure loads of a composite plate are compared with a nickel-aluminum-bronze plate. Discussions of the fluid and structural responses of both materials are presented, and the initial failure loads of both materials are compared.