The park displays a diverse ecosystem in floodplains of the upper Passaic River and its contributors and contains swamps, fields, forests, brooks, marshes, and meadows.
It is home to the Somerset County Environmental Education Center which contains 425 acres (1.72 km2) and provides educational services for visitors and contains a gift shop; it is also the starting point for a number of hiking trails for the exploration of the park.
The Lord Stirling Stable is an equestrian center with stables, an indoor arena, outdoor rings, and about 10 miles (16 km) of dedicated horseback trails in its 366-acre (1.48 km2) section of the Lord Stirling Park.
For thousands of years it has been inhabited, and current archeological sites explore the artifacts of the Lenape civilization.
The park is named after William Alexander, Lord Stirling, a general of the American Revolution whose estate included the area.