The Slate Islands archipelago is formed of two main islands, five minor islands and numerous islets located in northern Lake Superior

Lake Superior

Lake Superior is the largest of the five traditionally-demarcated Great Lakes of North America. It is bounded to the north by the Canadian province of Ontario and the U.S. state of Minnesota, and to the south by the U.S. states of Wisconsin and Michigan. It is the largest freshwater lake in the...

, 10 km (6.2 mi) south of the town of Terrace Bay

Terrace Bay, Ontario

Terrace Bay is a township in Thunder Bay District in northern Ontario, Canada, located on the north shore of Lake Superior east of Thunder Bay along Highway 17...

. The islands were created by a meteorite

Meteorite

A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...

 impact which formed a crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 about 32 km (19.9 mi) wide. In 1985, the Ontario

Ontario

Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

 government established the Slate Islands as a natural environment provincial park. The islands are notable for having Ontario's largest herd of woodland caribou.

The total surface area is about 36 km² (13.9 sq mi).