So. On 13 February 1997, the container ship Tokio Express was hit by a wave described by its captain as a "once-in-a-100-year phenomenon".
It almost capsized the ship one way - then almost capsized it the other.
And that meant that 62 containers were lost overboard about a few dozen miles off Land's End in Cornwall – and one of them was filled with around 5 million pieces of Lego, bound for New York.
The pieces are still washing up in Cornwall today – and have also apparently been found in Devon, Ireland, and Wales.
And – what are the chances? – many of the Lego items were nautical-themed. Loads of tiny cutlasses, flippers, and bits of scuba gear are appearing on the beaches.
Tracey Williams runs a Facebook page documenting the discoveries.
She recently got an email from someone in Melbourne claiming to have found a flipper from the spill.
The BBC interviewed US oceanographer Curtis Ebbesmeyer about the phenomenon.
He said: "The most profound lesson I've learned from the Lego story is that things that go to the bottom of the sea don't always stay there."
"The mystery is where they've ended up. After 17 years they've only been definitely reported off the coast of Cornwall."
