A trip to the remote north Pacific gyre provides a stark reality check on the scale of the planet’s plastic waste crisis. “You’ve been sailing at 10 knots for five days, you’re alone. You don’t see any other boats. And then you find toothbrushes and lighters floating around you,” says Laurent Lebreton, head of research at the Ocean Cleanup, a Dutch non-profit organisation that develops technology to extract marine plastics. “It’s just very surreal.” What he finds most striking, however, are the metres of netting, ropes and line, luminous orange buoys, crab pots and fish traps: remnants of the global...