(By TTC or GO transit: Take the subway or GO train to Union Station. It’s a ten-minute walk south from the ferry docks at the foot of Bay Street. Or take the Streetcar one stop from Union Station to the Island Ferry Docks. The docks is also served by the Bay St. bus. Get off at the Queen’s Quay stop.
By car: Parking around the ferry terminal is shamefully expensive. It can cost $20 – $30 for the day on weekends. Parking lots get full quickly so it may take some time to even find one with an empty spot, which isn’t fun in heavy traffic. It’s much cheaper to take the train or subway. (http://www.torontoisland.com))
More information can also be found at https://www.toronto.ca/explore-enjoy/parks-gardens-beaches/toronto-island-park/