The site is located in front of the Underwater and Oceanographic Research Station (STARESO), in the Bay of Calvi on the northwest coast of Corsica (France) in the Mediterranean Sea. This oligotrophic zone is classified as a “reference site” in the Mediterranean Sea because the environmental impacts due to anthropogenic pressure are low. A large Posidonia oceanica meadow occupies the seabed between -6 and -39 m.This meadow has been the subject of numerous studies for around fifty years. If the vitality of this meadow is considered as good, but the lower limit exhibits a regression since several years, possibly in relation with climate change (sea level rise /available light decrease). A monitoring based on SeagrassNet protocol is set up since 2006, the site is also included in the Posidonia Monitoring Network of Corsica.