Pope Francis on Saturday praised fishermen cleaning up polluted seas by collecting the rubbish caught in their nets and bringing it back to land to dispose of it.
Fishermen from San Benedetto del Tronto in Italy, who voluntarily collect around a tonne of litter a week and then sort it to be recycled where possible, met Francis at the Vatican.
"I would like to express my particular appreciation for the seabed clean-up," Francis told them.
"This initiative is very important, both for the large amount of waste, especially plastic waste, that you have recovered, and -- and I would say above all -- because it can and is already becoming a repeatable model in other areas of Italy and abroad".
Some 60 percent of the waste the fishermen collect is plastic.
The pope said the project was a great example of how civil society could to its part to help fix global problems -- and hoped it would inspire institutions to step up and shoulder their own responsibilities.
It is estimated that 80 percent of waste in the sea comes from land and 20 percent from boats and the fishing industry.
A study by the peer-reviewed Public Library of Science (PLOS) published in 2015 estimated that the Mediterranean contains 1,000-3,000 tonnes of floating plastic, with an unknown quantity on the seabed.
The Nile river delivers at least 1,500 tonnes of plastic into the Med annually, according to the PLOS study.
Sperm whales wash up regularly on Italian beaches, their stomachs full of plastic, and fishermen tell of getting so much plastic in their nets that it stops them being able to catch fish.
Much of the rubbish is single-use, such as bottles, plates and cutlery, but also includes old nets from fishing or mussel farming and assorted random plastic objects, from medical products to fax machine parts.