[2] In the 1940s, during World War II, Saint Helen's Island, along with various other regions within Canada, such as the Saguenay-Lac-Saint-Jean and Hull, Quebec had prisoner-of-war camps.

[3] The prisoners of war (POWs) were sorted and classified into categories including their nationality and civilian or military status.

After Expo 67, the site continued to be used as a fairground, now under the name Man and His World or Terre des Hommes.

Several important attractions are found on the island, including the Saint Helen Island Fort, the La Ronde amusement park, the Biosphere (an interpretative museum about the Saint Lawrence River installed in the former American Pavilion from Expo), and an Aquatic Complex (French: Complexe aquatique de l'île Sainte-Hélène) that includes three exterior pools.

The park is a primary recreational site for Montrealers and hosts frequent concerts and shows, including the L'International des Feux Loto-Québec international fireworks competition and the annual Osheaga music festival.

[5][6][7][8] During the summer season, on Sundays, electronic music fans can enjoy live DJs during the Piknic Elektronic event.