On February 13, 1997, 20 miles off the coast of Cornwall, UK, the container ship Tokio Express was hit with a massive wave. Sixty-two of the containers it was carrying were knocked overboard. The contents of 61 of those containers are either not known or too uninteresting to be publicized—but one of them held 4.8 million LEGO pieces, which have been washing up on Cornish beaches ever since.

An issue of Beachcombers' Alert from later that same year details the breakdown (by item) of the different LEGO pieces lost; in a weird coincidence, many of them happened to be nautically themed. There were, for example, 26,600 life preservers; 418,000 diver flippers in pairs of black, blue or red; 13,000 red or yellow spear guns; and 4200 black octopuses.

Seventeen yeas after the initial spill, beach goers are still finding these now well-worn LEGO pieces, but these days they have to hunt for them. "There's stories of kids in the late 1990s having buckets of dragons on the beach, selling them," Tracey Williams told the BBC earlier this year. She runs a Facebook group that documents the discoveries of these formerly lost-at-sea LEGOs by dedicated beachcombers. Because of their initial rarity, the octopus pieces have become a prize find amongst these treasure hunters; a recent post on the Facebook page depicts the visible, visceral excitement of the most recent discovery of one of the 4200.

American oceanographer and fellow beachcomber Curtis Ebbesmeyer estimates that since the spill, pieces could have floated some 62,000 miles—several times greater than the circumference of the equator, 24,000 miles. This means that ostensibly they could be anywhere, but thus far only finds in Cromwell have been confirmed.

"I go to beachcombing events in Florida and they show me Lego—but it's the wrong kind," he told the BBC. "It's all local stuff kids have left behind."

The pieces that are still being found look perhaps a little bit worse for the wear but have held up remarkably well after all these years at sea. The resilience of plastic is bad news for the environment—and along with treasure hunters, rogue LEGO pieces are sought after by beach clean-up groups—but it also means there will be collectors combing the sands for tiny octopuses and dragons until all 4,756,940 pieces are accounted for.

All photos courtesy of Tracey Williams/Lego Lost At Sea.