Over a period of approximately 1,900 years, beginning about 500 BC, the Native Americans at the Crystal River Site threw away great quantities of materials that would form the middens that adorn the site. This "midden material" contained various kinds of woodland animal bones, fish bones, turtle shells, broken pottery, broken hand tools and arrowheads. By the time of abandonment, the midden area had reached in length, in width, in depth, and was formed into a crescent shape. Two large platform mounds are believed to have been used primarily for ceremonial purposes. A paved loop trail passes by each mound, with signs interpreting the mounds. A 55 step observation deck atop the park's largest mound, Temple Mound, provides a panoramic view of the area. The park contains coastal marsh and is part of the Great Florida Birding Trail.