Sunnyside's western section, from the Humber River to west of the Bathing Pavilion is named in honour of Casimir Gzowski, a pioneer engineer in the building of railways in Canada. The park houses a monument built in the 1960s that has displays of his personal history. The park contains a children's playground and picnicking areas, a food concession stand, a stormwater catchment pond, and a leash-free dog area. The dog off-leash area is located to the east of the mouth of the Humber River.