Portus Julius

Portus Julius is an extraordinary underwater archaeological site in the Campi Flegrei area, where the remains of an ancient Roman military port built by Agrippa in 37 BC lie submerged due to volcanic bradyseism. Divers explore ancient quays, warehouse foundations, mosaic pavements, and harbor structures resting just meters below the surface. Fish swim through doorways that Roman sailors once walked through, and marine growth has softened the monumental stonework over two millennia. One of Italy's most significant underwater archaeological experiences, combining accessible beginner-friendly diving with over 2,000 years of naval history.