A WMS (Web Map Service) is a service that produces maps of spatially referenced data starting from geographic information, and is a technical specification defined by the OGC (Open Geospatial Consortium). This WMS presents the "Hydrography" layer of the Bodies' Territorial Reference Database (BDTRE), structured according to national technical specifications (DPCM November 10, 2011), collects the topics related to the description of water bodies, the coast and marine waters. The contents of this service are divided into the following levels corresponding to the BDTRE classes: - Internal and transitional waters - Marine waters - Perennial glaciers and snowfields - Hydrographic network The maps can be viewed using various software (e.g. QGis)