This area is a collaborative effort between Global Underwater Explorers (GUE) and diveRevolution Association to document, monitor and help in the protection of the Tyrrenhian Sea. Project Baseline Tyrrhenian Sea is the collection of biological, archeological, historical and environmental data of local marine sites, gathered through underwater survey, sampling and photographic/video tools. The project is a useful monitoring activity for the marine habitats and related sites. The investigation area extends from the southern part of the Ligurian Sea to the north of Sicily, including some of the most important islands in front of the coast, such as Capri, Ischia, Ustica, and others. The project started with a sample site (Mast of Capri), where a large amount of material was collected, and that has been very useful to evaluate and establish procedures for the future collection of standardized and widespread data. A data collection card, including the main information about the dive site like the physical (temperature, visibility, currents, sea bottom characteristic, etc.) and biological (identification of the marine species, with specific attention to the identification of ecological importance or interest anthropogenic specimens) is available.