The dataset consists of abundance records of 43 marine species in the Mediterranean Sea from 2001 to 2020. Selected species include some protected and non-indigenous species, ecosystem engineers, species sensitive to climate change, and/or threatened by human activities. Taken together, these taxa represent key ecological aspects of Mediterranean subtidal habitats (Cerrano et al., 2017) and can be used to calculate the MedSens, an index of the environmental status of subtidal rocky coastal habitats based on species sensitivity (Turicchia et al., 2021). Observations were carried out by the EcoDivers (trained scuba divers, freedivers and snorkelers) according to a rigorous protocol (RCMed U-CEM) developed by the association Reef Check Italia onlus.