Interaction of surface water waves with a floating platform is discussed considering nonlinearity of fluid motion and flexibility of oscillating structure. The set of nonlinear shallow water equations is applied to water motion interacting with a horizontally very large and elastic thin plate floating on the water surface. Calculation results of the floating thin-plate displacement due to the propagation of a tsunami, in terms of a solitary wave, are compared with the existing experimental data. Surface waves generated by the takeoff or landing of an airplane are simulated, such that when the offshore airport is constructed in shallower water, the slope of runway becomes larger and the complicated oscillation is harder to be damped down because of the reflection of floating thin-plate waves at the ends of the offshore airport.
