The Lost Villages of St. Lawrence

In the late 1950s the Saint Lawrence Seaway was built to bring  hydro-electric power to south eastern Ontario. On July 1, 1958, the cofferdams that had been holding back the water during construction were  blown apart, and nine villages along the St. Lawrence River disappeared forever.

8,000 hectares of prime farmland and mature orchards were destroyed by the flooding and 6,500 people were displaced. Aultsville, Dickinson’s Landing, Farran’s Point, Maple Grove, Mille Roches, Moulinette, Santa Cruz, Wales and Woodlands are now collectively known as "The Lost Villages". Ghostly remains of roads and other structures are still visible under the water.

There is a museum in Ault Park now near Long Sault devoted to the Lost Villages where you can see several artifacts salvaged from the communities.
More: Amusing Planet
Thanks Bruce!