Fern Canyon, Redwood State Park. Fern Canyon is a canyon in the Prairie Creek Redwoods State Park in Humboldt County, California, western United States. The park is managed in cooperation with other nearby redwoods state parks and Redwood National Park. It is named for the ferns growing on the 50-foot high walls, through which runs Home Creek. Fern Canyon is recognized as a World Heritage site and an International Biosphere Reserve.