Remember The Ocean Cleanup? It was the ambitious plan hatched by a young Dutch entrepreneur to "rid the world's oceans of plastic".
In 2013, 18-year-old Boyan Slat dropped out of an aerospace engineering degree after a TEDx talk he presented the previous year went viral.
In his talk, Mr Slat laid out his belief that a well-designed, floating system of nets could clean up the Great Pacific Garbage Patch — a concentrated gyre of plastic in the Pacific Ocean — "within five years".
Riding the huge wave of publicity after his presentation made its way to YouTube, Mr Slat launched a crowdfunding campaign, then a feasibility study, and eventually began working on prototypes for a system to remove from the world's oceans "90 per cent of floating plastic by 2040".
In 2018, after several years of testing, the System 001 prototype was launched — a 600-metre-long free-floating pipe with a net 3m deep suspended under it.