Thorah Island is located in the southeast portion of Lake Simcoe, approximately four kilometres from Beaverton, Ontario, Canada. Its coordinates are: 44.4288N by 79.164W. The island is approximately 1,450 acres (6 km²) in size and the land is divided mainly between wooded and wooded-swamp terrain. Some land has been cleared for farming and recreational purposes but much of the agricultural land has fallen into disuse and has grown over.
Thorah as well as three other islands in Lake Simcoe were ceded by the Chippewa Indians in 1856 to the British Crown on the agreement that the land would be sold and the proceeds invested for the descendants of the ceding chiefs. Following this sale William Napier made the first survey of the island in 1856.
Thorah was originally used as a recreational destination in the late nineteenth century by a group of four businessmen from Toronto who came to the island to camp and fish. The island currently (2004) has a seasonal population of 147 that include several descendants of the original group. 
The island was also named Canise (or Kanise) Ialand by Governor John Graves Simcoe in 1793 to honour a local native chief by that name. In the above-mentioned treaty between the natives and the British the island is known as Plum Island. Neither of these names are in popular use today.
- Strawberry Island is operated as a retreat for Basilican monks. This page also includes historical information about Thorah Island--particularly the details of the land acquisition from the natives.
- The Ontario Ministry of Natural Resources provides a technical description of the Island's environmental characteristics.