Marine biofouling is a major concern in the operational performance of submerged floating tunnels (SFTs). The objective of this research is to extend hydrodynamic conditions in experiments and numerically investigate the effects of marine fouling on the hydrodynamic behavior of SFTs, including flow characteristics and forces on the SFT subject to waves. A sensitivity analysis of roughness parameters including different roughness heights and roughness coverage ratios is carried out. Additionally, the hydrodynamic forces of a roughened SFT with a circular shape and a newly designed parametric shape are compared.