Coastal zones have been a dynamic area and most favoured locations utilized forliving, leisure, recreational activities, tourism, commerce and many other human ac-activities. Submerged and ﬂoating breakwaters have been used as eﬀective systems toprotect these zones from wave attack. However, they are only eﬀectively functionalif the incident wave height is relatively low. Under such condition, these systems canreduce the wave transmission with significant wave dissipation and hence achievinga desirable tranquillity in designated areas. Therefore, the focus of this research ismainly to investigate the possibility of using a combination of a submerged porousbreakwater (SBW) with a ﬂoating breakwater (FBW) as an innovative coastal protection system that can provide adequate calm conditions in the coastal zones withminimum visual impact. This study utilizes the open-source CFD model, REEF3Dto simulate such wave-structure interaction. This CFD model is based on the RANSequations coupled with the level set method and the k − ω turbulence modelIn the present study, the ﬁrst section deals with the simulation of irregular wavebreaking over an irregular bed proﬁle with the use of wave reconstruction methodto generate irregular waves. An excellent agreement between the computed resultsand the experimental data is obtained showing that REEF3D model is capable ofcapturing the dominant features of the evolution of the wave breaking process, bothin the shoaling region and the surf zone.The second section deals with the simulation of regular wave interaction with theSBW. The simulation is conducted using the VRANS method to resolve the porousﬂow. The wave interaction with the SBW is validated by comparison with experimental data. An impressive agreement between the numerical results and the experimental data is achieved with very small RMSE values. Finally, the validatedmodel is then used to simulate the combination of the SBW and the FBW. Threediﬀerent cases are investigated with three diﬀerent spacing between these structures.For each case, ﬁve diﬀerent conﬁgurations related to the geometry of the FBW aresimulated. It is found out that an eﬀective reduction of more than 90%, on average,of the incident wave height, can be achieved for this combined breakwaters system. This means that a transmission coeﬃcient (Kt ) of less than 10% is calculated acrossthis combination. Besides, it is found out that 1.75 FBW length to wavelength (L/λ)ratio produces a very low transmission coeﬃcient (Kt ). Further, an eﬀective distanceof 1-2 wavelength between the SBW and the FBW subsystems can also result inlower transmission coeﬃcients (Kt ).