Data on the presence and distribution of marine species during underwater visual census activities in the Gulf of Catania, Eastern Sicily, Ionian Sea. Data were collected on fixed line transects placed from 5 to 12 meters of deep, using scuba diving ARA equipment, and they include: date, time and geographical coordinates of the surveys, recorded species, size and number of individuals. The monitoring was supervised in years 2015 and 2016 by the MareCamp association.