Sediment transport in marine environments is associated with complex process. The development of mathematical modeling for suspended sediment transport in the late 20th century has provided a powerful tool for marine sediment dynamics. Effective running of the models requires appropriate algorithm and correct input parameters including the settling velocity of suspended matter, diffusion/dispersion coefficients for sediment, seabed roughness length, near-bed shear stress and the vertical (settling/resuspension) fluxes at the seabed boundary. For bed-load transport, empirical and semi-empirical formulae have been adopted, but these need further improvement, taking into account the factors of hydrodynamic setting, bed armoring, intensive activities of benthos, etc. Investigations into the physical processes and mechanisms for transport in the marine environment are needed to determine those parameters in suspended sediment transport models and to establish a more advanced theory for the physics of granular materials, which will be benefited by advancement in measurement technologies using instruments with high accuracy and resolution.