Furthering our understanding of the physical dynamics, chemistry and biology of permeable sediments is an important challenge for coastal scientists. Because muds and permeable sediments are fundamentally different, most information generated by studying muds is not directly applicable to permeable sediments, yet such sediments occur abundantly on continental shelves, on coastal beaches, in estuaries and in rivers worldwide. The geochemistry of fine-grained sediments is principally controlled by the gravitational settling of reactive particles from the water column, diagenetic reactions within the sediments, and molecular diffusive transport of solutes in the pore waters. Permeable sediments, however, may act more like fluidized bed reactors where advective transport supplies particulate and dissolved substrates and reactants at accelerated rates and removes potentially inhibitory end products. This system can support unexpectedly high biogeochemical reaction rates even at very low substrate concentrations. Additionally, most existing techniques for estimating reaction rates and benthic fluxes were developed for fine-grained sediments and generally will not yield accurate results in permeable sediments. The development of strategies and new techniques for quantifying fluxes in permeable sediments therefore also represents a major challenge. This session will highlight recent technological and intellectual advances in the study of the biology, chemistry and physical exchange processes in permeable sediments.