Waterloo State Recreation Area is the third-largest park in Michigan, encompassing over 21,000 acres (85 km2) of forest, lakes and wetlands.

Located in northeast Jackson County and parts of Washtenaw County, the park is the largest in the Lower Peninsula of Michigan and features 4 campgrounds, 11 lakes, a nature center, and over 50 miles (80 km) of trails - some for horses, bicycles, hiking and cross-country skiing.

The area is characterized by moraines, kettle lakes, swamps and bogs left by retreating glaciers after the last ice age.

The Federal Emergency Administration of Public Works studied the creation of a variety of kinds of parks in several states.

Sylvan Pond was created when the WPA put in a dam and levees at Cassidy Lake raised its water level permanently.

[1] The recreational demonstration projects were transferred from the Resettlement Administration to the National Park Service in November, 1936.

Public boat launches are located on the following lakes: Big Portage, Cedar, Green, Crooked, Mill, Mud, and Walsh.

The Gerald E. Eddy Discovery Center features exhibits on the geology and natural habitats of Waterloo State Recreation Area, both in pre-settler times and today.

Another display shows fluted spear points used by the Paleo-Indian hunters and other cultural history artifacts.