Sleeping Giant Provincial Park, established in 1944 as Sibley Provincial Park and renamed in 1988, is a 244 square kilometres (94 sq mi) park located on the Sibley Peninsula in Northwestern Ontario, east of Thunder Bay. The nearest communities are Pass Lake, located at the northern entrance to the park, and Dorion, located 35 kilometres (22 mi) NW, both in the township of Shuniah. The seasonal community of Silver Islet is located on the southern tip of the peninsula. The primary feature of the park is the Sleeping Giant, which is most visible from the city of Thunder Bay.
The park occupies most of the lower portion of the peninsula excluding the area around the seasonal community of Silver Islet, and a portion of Thunder Cape which is designated as the Thunder Cape Bird Observatory. The eastern portion of the park is lowlands, while the western half is terrain composed of cliffs, valleys, and the mesa–cuestas which make up the Sleeping Giant formation. At its eastern edge, it will touch the future Lake Superior National Marine Conservation Area.
The Sibley Peninsula is 52 kilometres (32 mi) long and 10 kilometres (6 mi) wide. It projects into Lake Superior from the north shore, separating Thunder Bay to the west and Black Bay to the east. The peninsula can be separated into two physiographic areas—highlands and lowlands. The highlands dominate the western half of the peninsula, and rise to 380 metres (1,247 ft) above the surface of Lake Superior. The lowlands of the eastern portion of the peninsula rise to only 75 metres (246 ft), over an area 3 to 6 kilometres (2 to 4 mi) wide. With the exception of diabase dikes and the large diabase sill that forms the upper portion of the Sleeping Giant, the peninsula is underlain by sedimentary rocks, which strike northeast and slope towards the southwest, forming a cuesta.
The varied terrain and the effect of Lake Superior on the peninsula's microclimates provide habitats for a wide variety of plants and animals. Plants found in the park include 23 species of orchids including Bog Adder's-mouth (Malaxis paludosa) and Small Round-leafed Orchis (Amerorchis Rotundifolia), two of Ontario's rarest species, as well as 22 species of alpine arctic disjuncts. Wildlife found in the park includes wide variety of mammals, the most dominant species being white tailed deer, black bears, and moose. Close to 200 species of birds have been recorded at the park, and about 75 species are known to nest in the park. The park is also home to a few species of amphibians and reptiles, and many species of fish.