In the area of today's Kaštel Štafilić, under the sea in Resnik, the remains of a Hellenistic port have been found. This paper presents important information related to the Hellenistic phase of the site, but with an accent on the Hellenistic port. The locality processing began with placing its setting in a geographical and historical context. The events that took place during the use of the port are described, and were initiated by the penetration of Greek colonists into the area of central Dalmatia. The history of the site's research is presented, as well as the events that influenced the current state of conservation. At the main part of the work is a detailed description of the port itself, from construction techniques to its use and role. Paper also provides a detailed description and analysis of the material found in the port, but also in the settlement itself. The use of the port and its role for the settlement and the surrounding area of Kaštela are explained. This work provides a clearer picture of the flow of materials and trade routes in that area.