The Ocean Cleanup’s 2015 Tsushima Plan and the Systems That Followed

In May 2015 The Ocean Cleanup, the organisation founded by Dutch inventor Boyan Slat, then 20, announced that it would deploy its first ocean-cleaning system off Tsushima, an island between Japan and South Korea. The plan called for a 2,000-metre floating barrier, which would have been the longest floating structure ever placed in the ocean.

The Ocean Cleanup’s floating barrier concept from 2015

Boyan Slat and the start of The Ocean Cleanup

Slat presented his idea of a passive ocean-cleaning system in a talk in Delft in 2012 and founded The Ocean Cleanup in 2013. The concept was simple to picture: long floating barriers would use ocean currents to gather plastic into one place, where it could be collected. In 2014 a crowdfunding campaign raised more than US$2 million to develop it.

Early Ocean Cleanup concept illustration of a floating barrier near an island coast — Concept illustration: The Ocean Cleanup.

The 2015 Tsushima plan

Tsushima was chosen because huge amounts of plastic wash up on its shores: about one cubic metre per inhabitant every year, according to the 2015 press release. The local government was looking for solutions and was studying whether the collected plastic could be used as an alternative energy source. Deployment was planned for the second quarter of 2016.

The 2,000-metre barrier would have beaten Tokyo’s 1,000-metre Mega-Float as the longest floating structure at sea. It was meant as a first step: within five years, the organisation hoped to install a 100-kilometre system to clean up about half of the Great Pacific Garbage Patch, between Hawaii and California.

From a North Sea test to System 001

In December 2015 the team announced a first barrier test in Dutch waters: a 100-metre segment placed about 23 kilometres off the Netherlands in the North Sea. The go-ahead for the Tsushima coastal pilot was pushed back so engineers could use the results. The 2016 test showed that conventional oil booms would not survive long at sea, and the floaters were redesigned in hard-walled HDPE pipe.

The project then shifted its focus to the open Pacific. System 001 left San Francisco on 9 September 2018 for the Great Pacific Garbage Patch. It caught debris but lost much of it, because the barrier did not hold a steady speed through the water, and in December 2018 an 18-metre section broke off. In two months it collected about 2 tonnes of plastic. The redesigned System 001/B followed in 2019.

How System 03 works today

The design that finally worked is towed, not anchored. The System 03 explanation published in 2023 describes a floating barrier up to about 2.2 kilometres long, with a screen hanging some 4 metres below the surface, pulled at walking pace by two vessels, the Maersk Tender and the Maersk Trader. Plastic is funnelled into a “retention zone”, which is lifted aboard when full so the catch can be sorted and packed for recycling.

Its predecessor, System 002 (“Jenny”), removed more than 250,000 kilograms of plastic from the patch between 2021 and 2023. System 03, deployed in August 2023, is nearly three times larger. The organisation estimates that around a dozen such systems would be needed to clear the whole patch.

Rivers, Interceptors and results

Since 2019 the organisation has also worked on rivers, the route by which much plastic reaches the sea. Its solar-powered Interceptor barges were first installed in Klang, Malaysia, and Jakarta, Indonesia, and later in Ballona Creek, Los Angeles. In July 2026 The Ocean Cleanup reported more than 60 million kilograms removed from rivers and the Pacific patch combined.

The approach has critics. Experts point out that less than 5 per cent of ocean plastic is thought to end up in garbage patches, and that shoreline collection may recover more plastic per dollar. Preventing waste from reaching rivers in the first place remains the biggest task.

You can help on your own coastline: carry your rubbish home and join organised beach cleanups. For clear seas to enjoy, see our guide to Greek beaches and water conditions.