Acoustic classification systems and the Sediment Trend Analysis method were used to identify and map the bed diversity in a very shallow(<3.0m),coastal lagoon,Pappas lagoon,Western Greece. Analogue acoustic data,collected by means of a 100 kHz side scan sonar system,were digitized and classified into six acoustic classes using recently developed acoustic classification systems (SonarClass,TargAn).By comparing the acoustic classes to ground truth data consisting of sediment grain size and visual inspection of the lagoon-bed,it is demonstrated that the six acoustic classes correlate well with the predominant surface sediment types and vegetation.Thus the spatial distribution of the classes can be considered to represent the spatial pattern of the sedimentary assemblages of the lagoon.The grain size trend analysis identified three dominant sediment pathways and directional trends which could be related to the predominant wind direction,the sediment influx through the inlets and the sediment supply from a small stream in the southern part of the lagoon.The integration of acoustic and sedimentological data together with advanced data processing systems leads to a better understanding of the sedimentary,morphological and biological processes in a shallow lagoon in different spatial and temporal scales and will therefore be beneficial to both sedimentological and biotic-diversity studies. Acoustic classification systems and the Sediment Trend Analysis method were used to identify and map the bed diversity in a very shallow (<3.0 m), coastal lagoon, Pappas lagoon, Western Greece. Analogue acoustic data, collected by means of a 100 kHz side scan sonar system, were digitized and classified into six acoustic classes using recently developed acoustic classification systems (SonarClass, TargAn) .By comparing the acoustic classes to ground truth data consisting of sediment grain size and visual inspection of the lagoon-bed, it is characterized that that the six acoustic classes correlate well with the predominant surface sediment types and vegetation.Thus the spatial distribution of the classes can be considered to represent the spatial pattern of the sedimentary assemblages of the lagoon. grain size trend analysis identified three dominant sediment pathways and directional trends which could be related to the predominant wind direction, the sediment influx through the inlets and the sedime nt supply from a small stream in the southern part of the lagoon. the integration of acoustic and sedimentological data together with advanced data processing systems leads to a better understanding of the sedimentary, morphological and biological processes in a shallow lagoon in different spatial and temporal scales and will therefore be able to both sedimentological and biotic-diversity studies.