Metcalph Bottoms is a day-use area popular for picnicking and swimming. From here you can walk one mile to Little Greenbrier School, a 19th-century split-log schoolhouse with original furniture.
Just west of Metcalph Bottoms along the Little River Road are two water attractions. The Sinks is a waterfall with a pool so deep it once swallowed an entire derailed logging train, or so they say. Swimming here is not recommended, but it is nice to sit and watch the water crash over the falls.
Close to the intersection with Highway 73, which goes to Townsend [1], is the Townsend Y, probably the most popular swimming hole in the park. The river here is relatively wide and smooth, and the grassy bank is perfect for sunbathing.
Links:
[1] http://www.moon.com/destinations/tennessee/great-smoky-mountains/gateways-the-smokies/townsend