A discovery at the deepest point of the Mediterranean Sea confirmed that human waste reached even the most remote parts of the basin. An international team of researchers descended aboard the manned submersible Limiting Factor to the bottom of the Calypso Deep, about 5,112 meters below the surface of the Ionian Sea, to document marine litter. This marked the first time a manned submersible visited the trench for scientific research.
During the 43‐minute survey the submersible traveled roughly 650 meters along the flat seabed and recorded 167 objects made of plastic, glass, metal, and paper. The research team calculated an average of 224 pieces of waste per hectare over an 850‐meter segment—equivalent to roughly 26,715 objects per square kilometer. The data, published in Marine Pollution Bulletin, indicated one of the highest concentrations of marine litter detected at such depths.
The debris consisted mainly of plastic, with almost 90 percent of the items being single‐use products such as bags, bottles, coffee cups with lids, and plastic sacks. The presence of paper waste suggested recent pollution. Researchers noted that lightweight waste was carried from coastal areas by ocean currents. “Part of the light waste, such as plastics, comes from the coast, from where they escape towards the Calypso Deep, just 60 kilometers away,” said Miquel Canals, professor in the Department of Earth and Ocean Dynamics and director of the UB Chair for Sustainable Blue Economy, according to Daily Mail.
The structure of the Calypso Deep—a trench nearly 20 kilometers long and about 5 kilometers wide with steep slopes, a flat bottom, and currents of around two centimeters per second—created conditions that favored waste accumulation. Underwater video footage showed linear alignments of debris that suggested deliberate dumping from vessels, as evidenced by a near‐straight furrow of piled garbage.
Only two species appeared on the seabed during the expedition—a grenadier fish and a crustacean. The limited marine life likely reflected the sparse biological environment at such depths, although the study did not establish a direct impact of the debris on these species. Further analysis using specialized software confirmed that the Calypso Deep trapped and accumulated vast amounts of waste. The study revealed that items reached the seabed through long‐distance ocean currents and direct dumping from ships. “Unfortunately, regarding the Mediterranean, it would not be wrong to say that there is not a clean inch,” said Canals, according to El Correo. He added, “It is necessary to make a joint effort between scientists, communicators, journalists, the media, influencers and other people with social impact. The problem is there, and it has an enormous scope, even if it is not directly visible. We should not forget about it,” said Canals, according to Daily Mail.
The article was written with the assistance of a news analysis system.