The park's Thunder Lake is a remnant of the ancient glaciers that covered Ontario tens of thousands of years ago. As these massive moving fields of ice shifted and melted, they left behind a huge lake called Agassiz. Over the years, Lake Agassiz receded creating hundreds of smaller lakes, like puddles after a rainstorm. Fringing Thunder Lake, are mixed forests of aspen, jack pine, white cedar and balsam, typical of the boreal region. The forest is home to moose, white-tailed deer and black bears.