This paper presents the analyzed results of an integration of three offshore wind farms (OWFs) and three seashore wave farms (SWFs) connected to an onshore large power grid through a high-voltage direct-current (HVDC) link based on voltage-source converter (VSC) to simultaneously achieve power-fluctuation mitigation and dynamic-stability enhancement. The performance of the studied three OWFs are simulated by three equivalent aggregated doubly-fed induction generators (DFIGs) driven by three equivalent aggregated wind turbines through three equivalent aggregated gearboxes. The characteristics of the studied three SWFs are simulated by three equivalent aggregated squirrel-cage rotor induction generators (SCIGs) driven by three equivalent aggregated Wells turbines through three equivalent aggregated gearboxes. A damping controller located at the inverter station of the VSC-HVDC link is designed by using modal control theory to offer adequate damping to the studied integrated OWFs and SWFs. Time-domain simulations based on a nonlinear-system model subject to a severe disturbance are carried out. It can be concluded from the simulation results that the proposed VSC-HVDC link joined with the designed damping controller located at the inverter can effectively stabilize the studied multiple OWFs and SWFs under various disturbance conditions.