Some frequent Shenandoah National Park hikers collect trails the way birdwatchers collect sightings. They check them off their list one by one. It is an impressive undertaking, since Shenandoah offers more than 500 miles of mapped trails, including a 95-mile segment of the famous Appalachian Trail.

Many trails are round trip -- to a specific site and back the same route. Others are circuit tours -- you return to the place you started without retracing your steps. And a few, such as any portion of the Appalachian, are one-way -- you walk in one direction and prearrange a ride back. You can link trails for a hike of whatever length you choose.

Good maps are advisable, especially if you are planning a longer hike. Park visitor centers have free maps to the most popular day hikes. Also available are topographical maps numbers 9, 10 and 11 of the Potomac Appalachian Trail Club. They cover the full length of the park and cost $3 each.

Among Shenandoah's most popular trails:

The trail to Camp Hoover: Used by Herbert Hoover as his weekend White House from 1929 to 1933, the camp can be reached via Mill Prong Trail (beginning at Milepost 52.8 on the Skyline Drive). It is about a four-mile round trip or a seven-mile circuit, returning by the Laurel Prong Trail and the Appalachian Trail.

White Oak Canyon: One of the park's most scenic trails, it descends alongside a cascading stream and pools to one of the park's highest falls. A round trip from near Skyland Lodge (Mile 42.6) is about four miles; a seven-mile circuit leads to more waterfalls.

Hawksbill summit: Hawksbill Mountain (Mile 45.6) is Shenandoah's highest at 4,051 feet. You have a choice of a shorter, steeper round trip (1.7 miles) or a longer, gentler circuit (about three miles). The views at top are great.

Traces Nature Trail: Here "traces" means remnants of the park's former mountain inhabitants. The trail begins at Mathews Arm Campground (Mile 22.2), taking you for an easy 1.7-mile circuit past a former homesite, rock walls and fields now overgrown. Markers tell the story along the way.

South River Falls: The 3.3-mile circuit (Mile 62.8) descends among spring and summer wildflowers to another of the park's highest waterfalls, this one not quite so heavily visited.