Analysis for the WWF to mark United Nations World Oceans Day reveals that there is a 40% increase in marine litter during the tourist season, and almost all of it is plastic.
More than 200 million people a year visit the Med, but a combination of litter on the beaches and poor waste management is making the sea one of the most polluted in the world.
It holds 1% of the world’s water, but contains 7% of all microplastic.
Tanya Steele, chief executive at WWF said: “The Mediterranean is a beautiful holiday destination enjoyed by millions of British people each summer, but when we come home with our happy memories we’re leaving behind a toxic legacy of plastic waste.
“The birds, fish, and turtles of the Mediterranean are choking on plastic.
“Our report also shows plastic is ending up in the fish and seafood we eat on holiday.”
WWF is appealing to holidaymakers to ditch straws, not to use wet wipes and think twice about buying inflatable pool toys.
The charity is also concerned about abandoned ghost fishing nets that continue to catch and kill marine life. They also release tiny plastic fibres as they degrade.
Sky News joined divers on the Greek island of Santorini who were removing nets and lobster pots that have snagged on rocks.
Teams from the organisations Healthy Seas and Ghost Fishing cut the gear free and lifted it to the surface. One of the nets weighed 200kg, yet even that is just a small dent in the 640,000 tonnes a year lost at sea.
Veronika Mikos, project co-ordinator for Healthy Seas, said the most lethal of all lost fishing gear is the gill net.
She said: “You can hardly see them, so they are dangerous for animals and dangerous for divers.
“They catch the fish by their gills and that attracts other marine animals like seals and dolphins who want to feed on the fish and they themselves become entangled.”
The nets recovered in Santorini will be recycled into a nylon yarn called Econyl, which is used to make clothing and carpets.
Conservationists from the Cousteau Divers organisation supported the ghost net mission.
Pierre-Yves Cousteau, founder of the organisation and son of ocean explorer Jacques, is campaigning for the area to be designated a marine conservation zone – with the UK unveiling plans to protect 41 new areas along its coastline.
Overfishing has almost wiped out stocks of commercial species, but he told Sky News that creating a protected “nursery” for fish would lead to an increase in catches for fishermen in surrounding areas.
He said: “You can associated the ocean to a sick person or someone who has injured themselves.
“When you injure yourself you rest and that is how you heal.
“Creating a marine protected area does exactly the same thing.
More from Sky Ocean Rescue
The ‘ploggers’ pick up plastic as they go running to save the world’s oceans
Sir David’s fears for marine life as plastic waste grows
Inventor hopes washing machine filter will save oceans from microplastics
Big expansion of UK’s ‘blue belt’ to protect oceans and curb plastic pollution
Prince Charles praises Sky Ocean Rescue bid to tackle ‘global plastics plague’
Sky leads major ocean summit in Cardiff
“The fish will come back and within five years we will see an increase in the fish biomass and biodiversity.”
:: Sky’s Ocean Rescue campaign encourages people to reduce their single-use plastics. You can find out more about the campaign and how to get involved at www.skyoceanrescue.com