The Switchback Trail starts from the entrance road, just before the pay station, but you will have to park in the lot just a few feet beyond the station. This is a 4-mile loop trail along the perimeter of the McKeldin area which lies within a large jagged-edged V formed by the confluence of the North and South Branches of the Patapsco River and Marriottsville Road.
About half of the trail lies along the river bank as it meanders along the valley floor. The trail starts with a gradual descent from about 460 feet down to the river at 300 feet in .6 mile. After about a half mile along the river, the trail gradually "climbs" back up to 400 feet before descending back to follow the river for about 1.5 miles. The initial part of the last ascent is the steepest part of the trail, and it is accomplished with a couple of short switchbacks. Presumably, the trail takes its name from this section, but it hardly fits this easy trail.
Highlights of my recent visit included a snake, which kindly posed for pictures; a hawk, which although it perched itself across the river for at least 10 minutes, it was just too far away to photograph clearly; and the inevitable Canadian geese. Can you find the hawk in the middle picture below?
If you have a good sense of balance, there is an alternative means of entering and exiting this part of the park. (The man on the opposite bank carried his bike across.)
Trails and Treasures Home Page Hiking Hiking in the Chesapeake Bay Area Patapsco Valley State Park