This paper numerically investigates the interaction between the Marangoni convection, the double diffusive convection and the intrusion force a multi-cavity system. The model consists of a two-cavity rectangular system in which the smaller cavity is located at the top left corner of the larger one. The larger cavity is filled with hot salty fluid while the smaller one contains cold fresh fluid. This problem is solved for the case of the fresh water intruding into the salty water. The interaction between the Marangoni (thermal and solutal) and the double diffusive regimes is investigated, for different solutal Rayleigh number, in detail. Finite element modelling results indicate that salinity induces stronger convection than the thermal ones and the thermal and solutal Marangoni convection further enhances the strength of the cellular flow. Numerical results indicate that surface force should be taken into consideration during the analysis and that the intruding force played an important role in the flow behaviour.