There are 600 miles of foot-blistering trails in the Olympic National Park, offering hikes of an hour to a week or more. A hearty day hike takes you far from the lazy crowds of windshield visitors. The medallion hikes are one-way trips across the million-acre park, either north-south or east-west, where you won't see a soul for days. Permits are required for all overnight stays in the park, but they're generally easy to get at the trailheads. Entrance fees apply.
First off, to do the ONP, you'll need a car. Now, as you look at a map of the Olympic Peninsula, look for three prominent park features: the Big Part, the Little Part, and The Highway. Start at the Visitor's Center in Port Angeles for an in-depth education about the park. That's about 2-3 hours from Seattle.
Big Part-- In this main part of the park you'll find trails from low-elevation rain forests on up to glacier-capped peaks. Roads enter the park at 15 points and all end at trailheads. The most visited are the northern entrances, most notably Hurricane Ridge and Crescent Lake. If you're looking for solitude, Elwha, Deer Park and Soleduck are less crowded. The rain forest entrance of choice is the Hoh River Visitor Center, but the Quinault Lake area is less used. The least-stampeded entrances of all are the southern Queets and North Fork, as well as the eastern Dosewallips and Staircase.
Little Part-- The beach-oriented part is a long, narrow stretch of park between the highway and the Pacific Ocean. The beaches, mostly pebbles with large rock formations, are reached by short trails. Camping and fires are permitted on most of the beaches, with the certain exceptions of popular Rialto Beach and Kalaloch (pronounced clay-lock). The triangle hike from Ozette to the beach and back is the best-known beach hike, and reservations are required. The enumerated beaches are your best bet for solitude--Beach One, First Beach, etc.
Highway-- US 101 circles the park's Big Part. No roads cross the park, so you'll use 101 to get around--and get around--the park. A winding two-lane road, US 101 can be a bummer if you get behind a logging truck or RV. For cyclists, 101 is a death wish. The highway doesn't complete its circle around the park, but adequate roads close the loop between I-5 in Olympia and 101 in Hoquiam. It's easy enough to reach 101 from Bremerton or Edmonds, too, using the ferry system from Seattle. Take a book for the long (2-4 hour) ferry waits on summer weekends and holidays.
Cautions-- Don't be fooled by warm weather and wide trails at the trailhead. Wilderness weather and trail conditions can change dramatically within two hours of the car. Wear boots and pack rain gear. Take warmer duds if you're heading into the high country, where temperatures are 10-30F degrees lower than at the beach. And be prepared for the usual mountain stuff, like snow and bears.
Beach camping has its hazards, too, the deadliest of which is high tide. Learn about headlands and overland trails; and spend $1 on a tide table before you go. Beaches are well-patrolled, so don't expect to camp, dig clams, or torch driftwood, if you're not supposed to. Reservations are required in some places, and permits are always required.