Because ONP sits on an isolated peninsula, with a high mountain range dividing it from the land to the south, it developed many unique plant and animal species (like the Olympic marmot[?] and Roosevelt elk[?]) that can't be found anywhere else in the world. Because of this uniqueness, scientists have declared it to be a Biological Reserve[?], and study its unique species to better understand how plants and animals evolve. A good book about the natural history of the region is Olympic National Park: A Natural History Guide by Tim McNulty[?].
Prior to the influx of European settlers, ONP's human population consisted of Native Americans, whose use of the peninsula consisted mainly of fishing and hunting. When settlers began to appear, the use of the peninsula (as with much of the Pacific Northwest) shifted toward harvesting of timber, which began heavily in the late 1800s and early 1900s. There wasn't much dissent against the logging until the 1920s, when people got their first glimpses of the clear-cut hillsides where trees had been logged. (The 1920s saw an explosion of people's interest in the outdoors; this occurred because the automobile allowed people to tour previously-remote places like the Olympic Peninsula.) Public desire for preservation of some of the area grew until President Roosevelt declared ONP a national park in 1938. Even after ONP was declared a park, though, illegal logging continued in the park, and political battles continue to this day (including President George W. Bush's declaration that logging restrictions must be eased) over the incredibly valuable timber contained within its boundaries. A good book detailing the history of the fight for ONP's timber is Olympic Battleground: The Power Politics of Timber Preservation by Carsten Lien[?].
There are several roads in the park, but none penetrate far into the interior. The park features a network of hiking trails, although the size and remoteness means that it will usually take more than a weekend to get to the high country in the interior. The sights of the rain forest, with plants run riot and dozens of hues of green, are well worth the certainty of heavy rain sometime during the trip.
A nearly unique feature of ONP is the opportunity for backpacking along the beach. The length of the coastline in the park is sufficient for multi-day trips, with the entire day spent walking along the beach. Although idyllic compared to toiling up a mountainside, one must be aware of the tide; at the narrowest parts of the beaches, high tide washes up to the cliffs behind, blocking passage. There are also several promontories that must be struggled over, using a combination of muddy steep trail and fixed ropes.