When you live along the coast, you get accustomed to seeing bizarre things wash ashore. Here's one thing you're not likely to forget, however: a solar-powered caravan-type houseboat, with no sign of a crew.

Three years ago, that's exactly what happened to a local in County Mayo, western Ireland, during a nightly beach stroll, reports CNN.

"It looked a little bit like a caravan. In the water, it seemed just a strange looking object really," said Michael Hurst, officer in charge at Ballyglass Coast Guard Unit.

The vessel was built of wood and was kitted with impressive solar arrays. Windows were lined on both sides, but there was no sign of a crew. As ghost ships go, this one was one-of-a-kind. So you'd think that tracing its origin would be easy, but despite significant media buzz around the strange boat, no one stepped up to claim it.

There was but one clue: a message scribbled on a wall inside of it. That message read: "I, Rick Small, donate this structure to a homeless youth. To give them a better life that Newfoundlanders chose not to do! No rent no mortgage no hydro."

This likely meant that the ship came from across the Atlantic Ocean, from Newfoundland in Canada. But how long had it been adrift? What accounts for its strange design? Who is Rick Small?

The mystery continued for three years — members of the coast guard unit and the local community eventually refurbished the vessel and donated it to a community sensory garden in nearby Binghamstown — until finally, the cold case was re-opened by an inquisitive reporter. Now, at last, the mystery has a solution.

Rick Small, it turns out, is a 62-year-old Canadian inventor who originally designed the oddball vessel as part of an effort to raise awareness about climate change. His plan was to sail from Newfoundland, through the Arctic Ocean and back again, to demonstrate how the sea ice is disappearing. He never quite managed to embark on the journey, and eventually decided to donate the ship to a local cause.

How the boat ended up across the Atlantic Ocean in Ireland, however, remains a complete mystery. It's unclear when exactly the vessel went missing, but clearly no one had been looking for it. Remarkably, it was sturdy enough to cross the Atlantic without anyone on board, and who knows where else it might have traveled.

"It didn't sink," Small said. "I must have done a good job, eh?"

Who knows, perhaps it even traversed the Arctic Ocean after all.

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Mystery of the solar-powered ghost ship that washed ashore 3 years ago finally solved
Ship with no crew drifted over 2,000 miles across the Atlantic Ocean.