An experienced skipper who is currently sailing through the world’s largest ocean rubbish patch has described how her stomach “clenched” when she was faced with the terrible reality of the planet’s plastic crisis.

Emily Penn is leading an all-women expedition through the Pacific Ocean on a mission to tackle the plastic pollution that is choking marine environments, killing animals and even threatening human health.

“The most alarming thing is just the number of pieces that are moving past the boat every time you look out,” says Ms Penn, a sailor with a history of environmental activism.

“You might get a bundle of fishing net, a washing basket, a chair; then you see bottle tops, toothbrushes, combs – people’s belongings basically. It doesn’t make any sense.”

Just as appalling, she says, are the endless tiny shards of plastic that fill the apparently empty spaces between the larger objects. These “microplastics” have been found in the stomachs of fish and shellfish around the world.

“That’s what we have been experiencing on a daily basis for the past 500 miles or so,” she says.

The eXXpedition crew, which consists of women from a variety of backgrounds including scientists, artists and sailors, departs Hawaii (thesituationroom.tv) (www.thesituationroom.tv)

At least 8 million tonnes of plastic is dumped in the ocean every year, and a large proportion ultimately ends up in one of the five major ocean gyres; drawn in by winds and ocean currents.

The largest of these gyres, dubbed the “Great Pacific Garbage Patch”, covers an area of 1.6 million square kilometres.

It is this enormous expanse that Ms Penn and her “eXXpedition” crew of scientists, sailors and artists is crossing on a trip that will take them from the plastic-strewn beaches of Hawaii to the shores of North America – the source of so much of this waste.

Plastic waste across the world: in pictures Show all 15 1 /15 Plastic waste across the world: in pictures Plastic waste across the world: in pictures A father and son on a makeshift boat made from styrofoam paddle through a garbage filled river as they collect plastic bottles that they can sell in junkshops in Manila. The father and son team earn some three US dollars a day retrieving recyclables from the river. AFP/Getty Plastic waste across the world: in pictures A composite image of items found on the shore of the Thames Estuary in Rainham, Kent. Tons of plastic and other waste lines areas along the Thames Estuary shoreline, an important feeding ground for wading birds and other marine wildlife. Getty Images Plastic waste across the world: in pictures Children collect plastic water bottles among the garbage washed ashore at the Manila Bay. According to the United Nations Environment Programme, at current rates of pollution, there will likely be more plastic in the sea than fish by 2050. AFP/Getty Plastic waste across the world: in pictures Plastics and other detritus line the shore of the Thames Estuary. In December 2017 Britain joined the other 193 UN countries and signed up to a resolution to help eliminate marine litter and microplastics in the sea. It is estimated that about eight million metric tons of plastic find their way into the world's oceans every year. Once in the Ocean plastic can take hundreds of years to degrade, all the while breaking down into smaller and smaller 'microplastics,' which can be consumed by marine animals, and find their way into the human food chain. Getty Plastic waste across the world: in pictures A dump site in Manila in 2013. The Philippines financial capital banned disposable plastic shopping bags and styrofoam food containers, as part of escalating efforts across the nation's capital to curb rubbish that exacerbates deadly flooding. AFP/Getty Images Plastic waste across the world: in pictures Children swims in the sea full of garbage in North Jakarta, Indonesia. Getty Plastic waste across the world: in pictures An Indian woman holds a jar filled with Yamuna river water polluted with froth and toxic foam to be used for rituals at the river bank in New Delhi, India. The Yamuna River, like all other holy rivers in India, has been massively polluted for decades now. The river that originates in a glacier in the pristine and unpolluted Himalayas, and flows through Haryana, Delhi and Uttar Pradesh before merging with the Ganges River in Allahabad, once used to be the lifeline of the Indian capital. Currently, it is no more than a large, open sewer that is choking with industrial and domestic discharge that includes plastic, flowers and debris and has virtually no aquatic life. EPA Plastic waste across the world: in pictures Plastic waste is washed up on South Troon beach in Scotland. Recent reports by scientists have confirmed, plastics dumped in the world oceans are reaching a dangerous level with micro plastic particles now being found inside filter feeding animals and amongst sand grains on our beaches. Getty Plastic waste across the world: in pictures Children collect plastic to be sold and recycled, in a polluted river in suburban Manila. The city's trash disposal agency traps solid waste floating down waterways that was thrown into the water by residents of slums along riverbanks upstream. AFP/Getty Plastic waste across the world: in pictures View of the Carpayo Beach in La Punta, Callao, some 15 km of Lima. In 2013, the NGO VIDA labeled the Carpayo Beach as the most polluted in the country - 40 tons of trash on each 500m2. AFP/Getty Plastic waste across the world: in pictures Trash from Kamilo Beach in Hawaii. Gabriella Levine/Flickr Plastic waste across the world: in pictures A scavenger collects plastic cups for recycling in a river covered with rubbish near Pluit dam in Jakarta. Reuters Plastic waste across the world: in pictures Rubbish fills Omoa beach in Honduras. Floating masses of garbage offshore from some of the Caribbean's pristine beaches are testimony to a vast and growing problem of plastic pollution heedlessly dumped in our oceans, locals, activists and experts say. AFP/Getty Plastic waste across the world: in pictures A man climbs down to a garbage filled river in Manila. Plastic rubbish will outweigh fish in the oceans by 2050 unless the world takes drastic action to recycle the material, a report warned in 2016. AFP/Getty Plastic waste across the world: in pictures Garbage on East Beach, Henderson Island (Pitcairn Islands), in the south Pacific Ocean. The uninhabited island has been found to have the world's highest density of waste plastic, with more than 3,500 additional pieces of litter washing ashore daily at just one of its beaches. EPA

Speaking to The Independent via satellite phone from the Sea Dragon, a 72ft (22m) scientific exploration vessel, Ms Penn described the low mood that set in as they entered the plastic soup.

“How do you convey – when you wake up on day four and you’re still seeing this plastic pouring past the boat. The feeling just makes your stomach clench,” she says.

The team is collecting samples and data that will then be sent to research institutions in the UK, Canada, Switzerland and the US.

The crew has come across all sorts of marine plastics including fishing nets and household items. Here they fix a tracker to a large pile of marine debris so researchers can track it and better understand ocean currents (eXXpedition)

This information is valuable, because owing to their remote locations there is still a lot scientists do not know about the Great Pacific Garbage Patch and other plastic accumulation zones.

Horrific images of turtles tangled in fishing nets and whales with stomachs full of bags have shocked the world, but the eXXpedition crew wants to investigate the subtler effects of plastic pollution.

Their samples will be examined for traces of chemicals like pesticides and flame retardants that have the potential to leach into the bodies of animals and – ultimately – humans.

The eXXpedition team is studying microplastics and toxics in the North Pacific Gyre, and they have found large amounts of microplastics in each sample collected (eXXpedition)

Being out in the open ocean has made the crew acutely aware of the interactions between wild animals and plastic waste.

“We are looking into the water and seeing fragments of plastic, and then 20m away we see an albatross feeding on squid which looks just like that plastic,” says Ms Penn.

The key to solving this problem, she says, is first to raise awareness and then to cut off the flow of plastic before it enters the ocean.

“There are trillions of fragments covering this part of the planet and it’s just endless, it goes on and on, and not only here in the North Pacific but other parts of the world as well,” says Ms Penn.