Yamaska National Park sits on the edge of Granby and is the easiest escape from the city for swimming, cycling, and walking. The park centres on a reservoir with sandy beaches that fill up with local families on summer weekends. The water is warm enough to swim comfortably from June through August.
The park has an extensive network of cycling and walking paths that circuit the lake and pass through marsh and forest habitats. Bike rentals are available at the park entrance. The marshes are particularly good for birding in spring (April–May) during the waterfowl migration; great blue herons nest in the area year-round.
In winter, the park stays open for cross-country skiing and snowshoeing on the same trail network. Admission fees apply; the park is managed by the Société des établissements de plein air du Québec (Sépaq).