This paper presents a comparison between different types of submerged abrasion platforms situated on the northern and southern coasts of Brittany (France). The aim of this comparison is to understand the spatial repartition of land forms in order to produce a tool for a later mapping of these submarine forms. The main sites for this comparison are St-Malo in the North (with a 13 m tidal range) and Belle-Ile in the South (with a 8 m tidal range), though many other sites have been explored during divinf field work. The first part of this paper is an inventory of land forms at a definite scale, depending on the observation technique. The observed forms are quite variable in size and frequency. Potholes are frequent; ridges and furrows are carved by differential erosion; submarine falls create field of blocks or submarine cones of clasts; ravine are infilled with coarse material or with sand. True erosional horizontal platforms, with a smooth surface are not quite common and are only observed in the North coast, close to the surface. We infer from this observation that true wave-cut abrasion platforms can only be localised close to the surface (in this case mean tide level) and are eroded or buried if they are submerged by more than a few meters of water. This implies that geomorphological heritages play a very important role, but in some locations only. The second part tries to explain the cause of the location os submarine land forms. If all forms, beside one, are found every where, they are not located whithout an order. Their spatial combination are very peculiar and reflect conditions of exposition, of sediment availability and of structural constraint. We try to present the spatial logic of the land form repartition. To achieve this understanding we have to determine which scale is efficient to explain which dynamics. This may lead to a better understanding of sedimentary movements. The last part presents a cartography of these submarine landscape. We include algal cover as an important element for the definition of this landscape. Some maps, at different scales, are shown and commented.