International audienceIstros, founded during the 7th century BCE, is one of the oldest Greek colonies on the shores of the Black Sea. On the southern margin of the Danube delta, what was an ancient maritime city is now a landlocked archaeological site. Even though archaeological investigations have continued since 1914, the location of the harbour(s) remains unknown. Efforts to find a harbour are hindered by the complex geomorphological evolution of the Danube delta and by the long human occupation history of the site. However, a new perspective is offered by a geoarchaeological approach, combining coring with geophysical and archaeological investigations