Olympic is also known for its biological diversity. Isolated for eons by glacial ice, the waters of Puget Sound and the Strait of Juan de Fuca, the Olympic Peninsula has developed its own distict array of plants and animals. Eight kinds of plants and five kinds of animals are found on the peninsula and live nowhere else in the world. In recent years, approximately 4 million visits annually.
Most roads remain open year round, although several are subject to winter closure because of snow.
Some campgrounds are open year round, while others close for the winter. Visitor center hours vary throughout the year. Winters are mild, with temperatures at lower elevations in the 30's and 40's. At higher elevations, snowfall is generally heavy, with accumulations of up to 10 feet common. Closer to sea level, much of the precipitation comes as rain, with some infrequent snow fall.