Tourists visiting the picturesque port at Cassis, southern France, often see an unedifying sight: plastic bags, discarded drinks bottles, and even used surgical masks, floating in the water among the boats in the marina.
But the port has found a solution, in the shape of a bright yellow remote-controlled electric powered boat that weaves around the harbour sucking the trash into a net that it trails behind its twin hulls.
The boat, called Jellyfishbot, is about the size of a suitcase and so can get into the corners and narrow spaces where rubbish tends to accumulate but which are difficult for cleaners with nets to reach.
"It can go everywhere," said Nicolas Carlesi, who has a PhD in undersea robotics and whose company, IADYS, created the boat.
It is not the only device of its kind. San Diego non-profit Clear Blue Sea is developing a proto-type trash-collecting robot called "FRED".
A marine technology firm based in the Netherlands, RanMarine, has developed a robot called the "Waste Shark" which has been deployed to clean up garbage in Rotterdam harbour.
"Jellyfishbot" is in operation in around 15 French ports, and has been exported to countries including Singapore, Japan and Norway, according to Carlesi's company. The firm has just launched an autonomous version.
A keen sailor and diver, Carlesi said he came up with the idea after noticing, whenever he spent leisure time on the water, how much rubbish bobbed in the water in ports.
"I thought: 'Why not try to make this difficult and sometimes thankless task of picking up trash easier?' So we made this robot," he said.