The Toronto Islands were once a peninsula, formed from a long series of moving sandbars created from the material Lake Ontario eroded from the Scarborough Bluffs, east of the islands on the lake. The sandbars were known to the Native people as a place of leisure, and at one point during European encroachment, the peninsula became known as the Island of Hiawatha.

On the map, the Toronto Islands consist of 12 islands: some attached by bridge, some accessible only by boat. Some so-called islands are in fact actually just a part of a larger island, and several of these islands are sometimes misnamed or misrepresented on popular maps. Ward’s Island is a part of Centre Island.  The Centreville Amusement Park is not on Centre Island; it is on Middle Island and Olympic Island. The Toronto Island Park is not on Centre Island, but Centre Island is sometimes called Toronto Island (singular).

Expect no cars and many bicycles. The two residential communities of Ward’s Island and Algonquin Island cover 40 island acres. The Toronto Island Park, which takes up 820 acres, offers beaches, lagoons to paddle on, amusement rides, and picnic spots galore.