Congaree National Park, South Carolina

Congaree National Park safeguards the largest intact old-growth bottomland hardwood forest in North America, with canopy heights averaging 100–130 feet. Its Champion Tree Trail features loblolly pines exceeding 500 years old, and the synchronous firefly event each May draws 10,000+ visitors to witness a bioluminescent display. This park's 26,000 acres flood annually, depositing nutrient-rich silt that fuels tree growth, making it a hidden gem for biodiversity.