Except for its campsites and hiking trails, much of Mississagi's land is undeveloped. The park is unspoiled, but for the still-noticeable effects of logging, and a forest fire in decades past.

The area is marked by a wave action on an ancient sandy beach, two billion years ago, that left fossils in an exposure of ripple rock. These ancient rock formations are rare and are protected as a valuable part of our natural heritage. They can be seen on the Flack Lake Nature Trail.

Other reminders of the past include glacial erratics -- huge boulders that were scattered through the park by the receding glaciers about 11,000 years ago, at the end of the last Ice Age. Relics from the logging and mining era in the late 19th and early 20th centuries can also be seen throughout the park and in displays at the visitor centre.

Native peoples have inhabited the park area for many centuries. Within the park today, there is evidence of old hunting and fishing camps of the Mississauga tribe.

Despite logging and fire, the park contains some massive old pines. It also contains upland forests of sugar maple and yellow birch, and many examples of white birch, trembling aspen, white spruce, and balsam fir.
The surrounding forest is home to moose, black bear and white-tailed deer, which may occasionally be spotted by patient wildlife observers -- especially those with binoculars. Mississagi is also host to abundant birdlife.