A mysterious 84-metre shipwreck has been discovered resting on the bottom of the harbour in Pictou, N.S.

Last month, the Canadian Hydrographic Service spotted the vessel while updating navigational charts in the area.

The ship, which is 84 metres long and 17 metres wide, had remained hidden in the depths over the years, only to be revealed thanks to acoustic sonar and 3D imagery technology used by the nautical authority.

"The interesting part of this is that it wasn't on the charts, most likely owing to the fact that technology of the time wasn't sufficient to capture the detail," Jon Griffin, a hydrographer for the Canadian Hydrographic Service, told CTV Atlantic.

The vessel, which has yet to be identified, is resting in about six metres of water and appears to be in good condition, with the exception of a gap in the middle and missing superstructure – the parts of the boat that are above the deck.

"It's on the edge of the channel … there's no rigging. There's no house. (But) the boat appears to be just sitting intact on the bottom," said Griffin.

The ship's origins and the circumstances surrounding its sinking have yet to be traced.

And it's led to plenty of speculation, including historian Clyde Macdonald's theory about it being a vessel called "The Favourite," which sailed from Scotland to Pictou in 1802.

"As soon as the 500 passengers were taken off the ship and all of cargo was taken out … the ship sank," said Macdonald.

"Rollie Sherwood, a noted historian from Pictou, stated in his book that it was witchcraft that caused it to sink," he added.

The wreck will be marked on new marine charts and more details could be on the way as the Canadian Hydrographic Service plans to send a camera in to explore.

"As time and opportunity permits, (we'll) drop a camera over. (But) the water is awfully murky, I have no idea what we'll see," said Griffin.

Pictou is a town about 160 kilometres northeast of Halifax.

With a report from CTV Atlantic's Dan Macintosh