The discovery of a sunken ship in Arctic waters may resolve a mystery that's more than 150 years old.
Divers believe they have found the wreck of the HMS Terror, which was trapped in ice in 1848.
But the discovery has raised even more questions about what happened to the ship and her occupants.
The story of the Terror belongs to a completely different world. It set off with the great British Polar Explorer Sir John Franklin to try to complete the North West Passage.
It disappeared and the Navy spent 11 years looking for its crew.
HMS Terror set off from Greenhithe in May 1845 and it was last seen entering Baffin Bay in August that year.
It's not known what happened to the expedition but historians believe the ship was abandoned in heavy sea ice off the coast of King William Island.
It was discovered again now in Terror Bay, more than 90 kilometres south of where it is thought to have been left. So what happened?
"The story used to be that they abandoned ship and marched off to their deaths," naval historian Professor Andrew Lambert says.
He says it looks as though the ship was reboarded by members of the crew and sailed to Terror Bay, where it then sank.
"But we still don't know why they ran out of food, what happened to the expedition, and we don't know what they did with the scientific data they gathered," Prof Lambert says.
"But this ship may help us to get further into what is the greatest mystery in history of the Arctic."
In short, a wreck discovered by chance that might finally yield an answer to a very old question.