One of Canada’s busiest harbours during the 18th century was located at Cape Breton’s Fortress Louisbourg.

Canada’s only team of underwater archaeologists are now searching the waters in Louisbourg and keeping an eye on the history below.

On Wednesday, the team searched the 250-year-old ruins of The Celeb, a 64-gun French warship that once protected the harbour.

“We return from time to time to Louisbourg to check up on the wrecks and see if there is any change,” says archaeologist Jonathan Moore.

The team dives into the chilly waters to do maintenance work and scrape kelp from the fragile structures.

They are also armed with underwater cameras and video equipment, capturing images of seven wrecks that remain from the 18th century.

The team scours the sea for artifacts from a time when Louisbourg Harbour was a battlefield between the French and the English.

“In Louisbourg, we have a treasure trove of 18th century shipwrecks, all of them related to the sieges here,” says Parks Canada Cultural Resources Manager David Ebert. “Some of them were sunk deliberately to try and keep the British out of the harbour, some were sunk during battle.”

Parks Canada has been monitoring the shipwrecks since the 1960s and members say the condition of the ships have held up over time.

“I don’t think people realize what a unique resource we’ve got here and what a wonderful diving opportunity there is here,” says Ebert.

For those who aren’t divers, there will be an opportunity to explore the shipwrecks’ secrets this summer. An archaeological festival has been planned as part of the Louisbourg 300 celebrations.

With files from CTV Atlantic's Randy MacDonald