In 2020, an emergency excavation on the northern shore of the Poreč/Parenzo peninsula (Istria, Croatia) revealed the presence of a large Roman quay dating from the beginning of our era. The site was rehabilitated in the second half of the 1st century: the wreck of a sewn ship, sunk at its foot, served as a foundation for a fill made up of building material and ceramic furniture. This reorganisation was intended to facilitate access to the sea, which had retreated with the filling in of the seashore following the development of urban activities. The study of the material has made it possible to extend the use of the port to late antiquity, when other structures and a medieval tower are superimposed on the quay. A very large submerged structure in front of the northern shore of the peninsula, the Porporella, was also the subject of investigations in 2019 and 2021. It consists of a pile of stones thrown over 400 m long and a width of between 4.5 and 12 m This research is part of new studies on the port of Parentium, about which little or nothing is known because the construction of the modern quays has sealed off the ancient levels. This port, with its excellent nautical qualities, must have played a major role in ancient times for the export of the territory's products. Even in the Venetian period, Poreč was an outport of Venice. The excavation of the Porta de Mar confirms that the Roman port must have been located to the south, on the site of the medieval and modern port, while the Porporella is a breakwater designed to protect the northern shore of the city. The fieldwork was accompanied by a review of the archival documentation.