The mechanical response of submarine masses under the action of sea wave loads is studied in this work. The saturated deposit below the seabed is modeled as a fully saturated poroelastic medium according to Biot’s theory, while the dynamic load acting on the seabed is obtained from Stokes’ theory. Both dynamic and quasi-static analytical solutions are presented, together with discussions of alternative approaches for the solution of the dynamic case. Furthermore, comparisons in terms of pore pressure, displacements, and effective stresses under various scenarios of seabed and wave properties are also assessed, so that the importance of inertial effects can be quantified. Preliminary results indicate that the quasi-static solution can be used with safety when the wave loading period is less equal than 10 s for massifs with soil permeability ranging from 10–5 and 10–2 m/s under water depth to wave length ratios up to 0.8. Finally, a simplified stability analysis is proposed to identify potential zones of soil failure. The potential areas are wider for thinner soils, but this trend decreases as the dynamic pressure acting on the seabed is reduced.