Viewed from space, the endless blues of the Pacific Ocean are the most obvious feature of Earth. Though not visible to those orbiting our planet, of equally vast proportions – and fast-becoming the Pacific’s most notorious feature – is the Great Garbage Patch.

This oceanic gyre, or set of gyres, covers areas in the North Pacific where surface currents and wind aggregate plastic waste of various sizes. The Great Pacific Garbage Patch spans the entire North Pacific ocean, stretching from the west coast of the United States to Japan.

Scientists believe it is actually comprised of two spinning areas, one in the north-east Pacific, the other centred in the north-west. The Hawaiian island chain sits slightly below and between them. The two patches exchange floating debris in a subtropical convergence zone, where cold currents coming down from Alaska meet warm currents coming up from the equatorial Pacific.

Because the whole of the North Pacific has circular currents along its boundaries, material flushed into the sea from coasts tends to keep getting swept along and, as if in a whirlpool, it congregates towards the centre.

Log on to vessel tracking websites and you may be able to see two small ships determinedly trying their best to clean this patch up: the Danish-flagged Maersk Trader and Maersk Tender. Both might be steaming at just a knot or so, side by side, and have been on their latest plastic harvesting in the subtropical Pacific since March 2024.

The Maersk Trader and Tender are conjoined by a tow. Two plastic wings pull along a device that sweeps floating plastic into a seine net. This huge sack is known as the Retention Zone. Once this collecting device is ready to be emptied, it is hauled aboard one of the ships. The plastic is emptied out on the afterdeck, sorted and packed. The Retention Zone is slid into the sea once again to trawl up more plastic. Little by little, these two ships are trying to clean up the world’s biggest ocean.

Ambitious goals

The Ocean Cleanup concept began in the Netherlands 11 years ago, when then-schoolboy Boyan Slat started thinking of ways to collect the marine litter he’d seen on a scuba-diving trip in the Mediterranean. He dreamt up a plan to use plastic retention devices with gathering wings like manta rays. Perhaps, he thought, they could be anchored to the seabed, and currents could wash the rubbish into the floating receptacle.

In his summer holidays he approached yachtsman Florian Dirkse to ask for help in developing a professional feasibility study. Dirkse is a full generation older than Slat, but they went to the same high school. The feasibility study plan was still in progress when Slat enrolled in an aerospace engineering degree in the city of Delft.

Dirkse says he and Slat listed 35 questions that the incipient project needed to answer. They decided to start a research foundation – Dirkse’s network of maritime contacts proving particularly useful at this point.

“We called it ‘The Ocean Cleanup’ because ‘OceanCleanup’ was not a free URL,” Dirkse recalls. It’s been a big shift from those early shoestring days to the organisation’s current financial health and high profile (its 2023 annual report showed that in 2022 the non-profit organisation had a budget of €53 million).

“We started a crowdfund campaign gathering $90,000,” explains Dirkse. They also created a Facebook page. Then came the turning point for The Ocean Cleanup: in 2012 Boyan Slat gave a persuasive presentation at a TEDx event in Delft. “I believe,” said Slat, “the Great Pacific Garbage Patch can completely clean itself in just five years.”

It was a simple plan. Humans could harness natural processes to clean up a blight they had created on nature. A YouTube video of his passionate TEDx talk has since garnered more than 3.3 million views. “It went viral,” Dirkse says, with understatement. “Really we didn’t know what was happening. First we wanted to prove the project’s feasibility.”

The project rapidly escalated. “We needed volunteers just to help with communications. One day we got 1,500 emails. It went completely crazy,” recalls Dirkse. In just 100 days, the crowdfunding campaign raised over US$2million – the most successful non-profit crowdfund in history, according to ABN Amro bank.

The narrative was so simple it was easily communicated and, critically, lent itself to being rapidly and widely reshared on social media.

“[By] letting the rotating currents do their work,” said Slat in the TEDx video, “vast amounts of funds, manpower and emissions will be saved.” He said the floating collection platforms would be “completely self-supportive, receiving their energy from sun, currents and waves.” And revenue could be made from selling the plastic retrieved. “It’s profitable.”

Few could question Boyan Slat’s belief. As the video went viral, investment followed and the project gathered pace. Florian Dirkse left The Ocean Cleanup owing to demands on his time – the start-up project meant 80-hour weeks were not uncommon – but he’s keen to stress that he feels The Ocean Cleanup has so far done ‘an amazing job’ and he sees a bright future for the organisation he co-founded.

The dream became reality when – after 273 scale model tests – the first ocean-sweeping device was deployed in the northern Pacific high pressure zone in 2018.

Out of the ocean

The first iteration was a floating boom, hundreds of metres long, with a 3m net hanging underneath. The net was pushed along by the current at the same speed at which the current pushed along the plastic. According to analysis by the Australian Broadcasting Corporation, the system did not collect as much plastic as originally had been envisaged. The Ocean Cleanup itself describes the next stage as going back to the drawing board.

In 2021 a modified system was brought in, with ships towing the boom, and a collecting device in the middle – System 02, otherwise known as ‘Jenny’. In 2023, The Ocean Cleanup opted to pursue this model at scale.

In the current System 03 the ships tow a vast 2.2km long boom with a net hanging 4m below the surface. So far 565 tonnes of plastic have been retrieved from the Pacific, according to the organisation’s live dashboard in May 2024 (data is verified when the vessels return to shore) – undeniably a huge achievement.

But Florian Dirkse admits the plastic retrieved from the gyre is ‘really nothing yet’ in comparison with the amount still floating out in the ocean. He recognises that the amount collected is difficult to balance with the costs of burning fuel to get there, though says: “You have to start somewhere.” His hope is the original plan of connecting the retrieval devices to the seabed and letting the currents do the work can be revived in some form, “I really hope it’s an inbetween phase.”

The initiative has attracted harsher critics. Dr Ewoud Lauwerier, plastic policy expert at Swiss conservation group Ocean Care, worked on a joint report to a UN conference last year. Dr Lauwerier is sceptical about The Ocean Cleanup. The concept of “ocean vacuum cleaners”, he says, is “attractive, but misleading. They are ineffective, capital intensive, falsely seen to be a solution and can even harm marine wildlife.”

The Pacific, Dr Lauwerier says, is “an incredibly complex system. And they’re adding kind of a huge vacuum cleaner without much reflection of its impact… What happens to the fish, turtles and marine mammals?” The Ocean Cleanup’s report states that 99.7% of the total catch consisted of plastic, with 0.3% marine life bycatch. The net also includes a Marine Animal Safety Hatch (MASH) – if an animal is spotted on the system’s underwater cameras, an exit hatch is opened allowing them to swim freely out.

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According to Waterhaul, a British social enterprise specialising in plastic retrieval, fishing gear is the biggest problem when it comes to trapping wildlife. “Nets are the most abundant form of plastic in our oceans,” explains Waterhaul’s founder, former marine scientist, Harry Dennis. “They’re lethal because of a phenomenon known as ‘ghost fishing’. Marine life that is entangled in these nets attracts more species, resulting in an ongoing loop of catches. As these discarded nets are produced from plastic, they will not degrade, persisting in the ocean to catch and kill marine life indefinitely.”

Another big concern around The Ocean Cleanup concept is the fuel required: not just to keep the propellers of Maersk Trader and Tender turning, but to handle the extra loads and tensions arising from towing the boom structure. Lauwerier questions the capital expenditure of the project. The costs of chartering vessels include the running costs of bituminous bunker fuel, lubricant, maintenance, repair and crew. On balance it might appear that the charter costs outweigh the recycling value of recovered plastic.

I put it to Dr Lauwerier that the spirit of entrepreneurship allows for repeated failure. “Each time you fail, fail better,” is a shopworn corporate slogan, but it epitomises a determination to succeed. Lauwerier is less forgiving: “It’s really a Silicon Valley mentality. They see themselves in that way. As very smart engineers. A lot of them are from the same background, mainly young people with experience of the offshore industry. They have very few biologists or marine environmentalists.”

However, what Lauwerier deems a ‘Global North Approach’ has also brought in big investment and attracted wide media attention to the problem.

So what would a local approach, not centred in the developed world, look like? Giff Johnson, editor of the main newspaper in the Republic of the Marshall Islands, was intrigued to learn of the Ocean Voyages Institute, a separate organisation based in California which aims to get sailing vessels to retrieve plastic on a smaller scale than The Ocean Cleanup.

In 2022 the Ocean Voyages Institute chartered a Marshall Islands’ government vessel, the SV Kwai, from the Marshall Islands Shipping Corporation. The ship helped volunteer yachts place satellite beacons on drifting abandoned fishing nets.

Guided by these beacons and its own drone equipment, the Kwai was then sent to collect the debris. Besides marine life, a lot of floating plastic also gets swept up in abandoned fishing nets: bottles, fishing floats, crates, chairs, rope, all get sucked into balls of rubbish trapped in the net mesh.

Can sailors help?

Can yachtsmen make a difference? Lauwerier advises against cruisers making a detour or putting themselves in danger to collect plastic, but leaving a beacon on it to alert local fishermen might be the best option.

Back in the UK, Harry Dennis of Waterhaul also encourages sailors to report the presence of ghost gear via his website. “When we have the mechanisms in place, where safe to do so, collecting nets and dropping them off at one of our collection points would also be a brilliant help – we’re in early talks to make this happen with boatfolk marinas,” says Dennis.

Supporting local projects for more labour-intensive cleaning is another method whereby sailors can help. Steve Green heads Clean Ocean Sailing, which like Waterhaul, is based in Cornwall. The only trawling that Clean Ocean does, he explains, is in conjunction with the Five Gyres organisation. This is essentially sifting for microplastics rather than collecting anything. “A tiny net the size of a breakfast bowl is towed behind a boat at 2 knots, or slower. You log your position and retrieve the trawl, to sample the microplastics.”

Beach clean

“The best way [to remove plastics] is to wait until it washes up,” says Green. His operation consists of tiding their small yacht down the Helford, then rowing ashore when the tide is ebbing or out. The wooden boat, George, is beached and then the litter-pickers get to work. It is, he says, immensely satisfying when George “with a tonne of waste inside”, is lifted effortlessly on the tide, and the plastic brought back to the mothership.

“Sometimes I struggle with the question of how to make a difference,” he says. “Then we land on a tiny beach, picking up the plastic, leaving it pristine. If everyone did something, we could make a big difference.”

There are, Green says, scaled-down versions of ocean gyres within riverine and coastal tidal eddies. Working with them gives a direct understanding of larger systems. “After the River Fal joins the Helford, off the Manacles [rocks] in certain conditions there is a gyre, a 1-2 mile long patch of floating stuff. We’ve drifted in there to do litter-picking.”

Looking directly at the Manacles patch helps you see very quickly the challenges The Ocean Cleanup has faced.

“In there you have seawood and driftwood. Trawling through, very clearly you’re going to have by-catch. You can see how on the ocean trawling for plastics on the surface is going to catch dolphins, turtles and sharks.”

Clean Ocean Sailing was founded seven years ago to clean up plastic from parts of the Cornish coast not easily accessible by land. Ten tonnes of waste have been collected by volunteers each year, amounting to an impressive 70 tonnes over its period of operation.

Green is also working to ensure more of the fishing gear they retrieve can be recycled – he’s been liaising with Polyform, the Norwegian fishing float manufacturer, about making floats from an alternative material to the non-recyclable PVC.

At the source

The Ocean Cleanup is, despite its moniker, achieving its greatest successes in removing a great amount from rivers directly. Nine thousand tonnes, in fact, according to their blog. In 2019 The Ocean Cleanup announced new projects targeting the world’s rivers. Interceptor craft have been at work in Thailand, Indonesia, Vietnam, Malaysia, the Dominican Republic and the United States – perhaps The River Cleanup would be a more apt name.

Cleaning rivers, Florian Dirkse says, brings many positives. “People can see it. It’s visible to local people. It’s a lot cheaper to catch plastic here than in the ocean. It’s really the future.”

• The Ocean Cleanup declined our request to speak with Boyan Slat for this article

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