The 22-gun British warship HMS Ontario sank during a storm on Lake Ontario in 1780, and divers have been looking for her ever since. Now they’ve found her, and she’s apparently in great shape.

“Usually when ships go down in big storms, they get beat up quite a bit,” Mr. Scoville said. “They don’t sink nice and square. This went down in a huge storm, and it still managed to stay intact. There are even two windows that aren’t broken. Just going down, the pressure difference, can break the windows. It’s a beautiful ship.”

Mr. Smith, who was shown underwater video of the discovery, said, “If it wasn’t for the zebra mussels, she looks like she only sunk last week.”

The dark, cold water acts as a perfect preservative, Mr. Smith said. At that depth, there is no light and no oxygen to hasten decomposition, and little marine life to feed on the wood.

They’re not releasing the location to keep her safe from looters, and she won’t be raised. She was carrying 130 British troops when she went down, so the site is a de facto war cemetary.