The four-man team said it found the wreck of the Nisbet Grammer in more than 150 metres of water 13 kilometres off Somerset.
The ship was hauling a load of grain from Buffalo to Montreal when it collided with the steamship Dalwarnic in dense fog early on the morning of May 31, 1926. The stricken ship sank in less than 15 minutes, but all aboard were saved by the crew from the other steamer.
A six-year search for the sunken ship ended in August when the team's side-scan sonar detected the wreck, said Jim Kennard of Fairport.
The Nisbet Grammer, named for one of its Buffalo-based owners, was launched from a shipyard in England in 1926. It was known as a "canaller," a type of steamship used to transport grain, coal and other products through Ontario's Welland Canal to ports on lakes Erie and Ontario.
The ship was the largest steel steamer to have sunk in Lake Ontario, Kennard said. The team surveyed more than 200 square kilometres of lake bottom until finding the wreck site in late August, he said.
A remotely operated vehicle was used to obtain video of the shipwreck and identify it as the Nisbet Grammer, Kennard said.