In 1997 a freak wave washed 62 containers into the sea off a cargo ship near the coast of Cornwall. Inside one were five million pieces of Lego. By a strange quirk of fate, many of the Lego pieces had a sea theme. This is the story of the community of beachcombers trying to track down the miniature octopuses, scuba tanks, life rafts, flippers, sharks and some very rare green dragons still washing ashore today.

Beachcomber Tracey Williams set up the social media account Lego Lost At Sea, allowing people to share their finds. She leads BBC reporter Robin Markwell on a journey around the Cornish coastline looking for the tiny toys.

On the way they meet fishermen still bringing up Lego in their nets, families brought together by dragon-hunting and an artist making sculptures out of millions of pieces of microplastic. Lego Overboard is a tale about the joys of treasure-hunting with a serious message about the long-lasting legacy of plastic pollution in our seas.

Producer: Robin Markwell for BBC Audio in Bristol