Since the first archaeological excavations undertaken in the 1970s/1980s, Tel Akko is known to have been an important trade city from the early 2nd millennium B.C. onwards. Even if the site has been intensively excavated, no paleoenvironmental studies looking to understand coastal changes near the tell since the Bronze Age had been undertaken until recently. Our research is based on the study of sediment cores drilled at the foot of the tell and in the Old City of Akko, 1,500 m west of the tell. We validate the coastal changes, already proposed by previous studies, while clarifying the chronology of these changes. We propose that the southern anchorage was located in the river mouth of the Na'aman until the early Persian period. This anchorage shifted to the "open" western coast of the tell during the Persian period before its subsequent relocation to the rocky promontory of Akko in Hellenistic times. We attempted to locate the Hellenistic harbor of Akko by coring in the Old City, in proximity to the modern harbor. At that time, a harbor lay in a semi-protected pocket beach at the foot of the promontory. K E Y W O R D S ancient harbor,