Sunnyside Amusement Park (also known as Sunnyside Beach Park) was a popular amusement park in Toronto, Ontario, Canada that ran from 1922 to 1955, demolished in 1955 to facilitate the building of the Metro Toronto Gardiner Expressway project. It was located on the Lake Ontario waterfront at the foot of Roncesvalles Avenue, west of downtown Toronto.
The name 'Sunnyside' was the name of a local farm owned by John George Howard, which was situated just to the north, on the location of the current St. Joseph's Medical Centre. Sunnyside Avenue runs north-south from that location north to Howard Park Avenue today. John Howard is also famous as the original landowner of the nearby High Park.
Prior to the construction of the park, the shoreline was a narrow stretch immediately to the south of the 1850s era rail lines. There was enough area for a restaurant and a small fenced off area was provided for changing into swimwear. To the east, the club-house of the Parkdale Canoe Club jutted out into the lake.
A plan was developed in 1913 by the new Toronto Harbour Commission to improve the shore lands from the foot of Bathurst Street to the Humber River. The plan, which included four miles (6 km) of breakwater, infilling of land, and the construction of the Lake Shore Boulevard, cost $13 million, and was paid for by the federal government.
A boardwalk along the south side of Lake Shore Boulevard was built, from the Humber River east to Wilson Park Avenue, 24 feet (7.3 m) in width using white pine planks. This corresponded to the length of shoreline that was extended out into the lake. This boardwalk became the site of annual Easter Parades until 1953. It was rebuilt in 1934 as a make-work project and was paved using asphalt in the 1960s.
The Amusement Park lands themselves were completely created from sand dredged from the bottom of the bay and top soil from a farm in Pickering, Ontario. The original shoreline was extended into the lake by approximately 100 metres, from the foot of Wilson Park Avenue west to the Humber River, a distance of about 1 kilometre. Only a small length of the original shoreline and beach exists today, located between the Boulevard Club and the Canadian Legion building at the intersection of Dowling Avenue and Lake Shore Boulevard.