Overgrown, lined by enormous trees and encroaching ferns, with peek-a-boo views of the former Elwha Dam site, Smokey Bottom is a good way to get in a mysterious-feeling 4 miles of walking after visiting the interpretive area near the former dam site.
From the parking area, set out on a trail behind a sign that reads:
Boulder River 2.0
End of Trail 1.9
Despite the potentially confusing signage, never fear. You'll be rewarded by a view of Boulder River at the end. The trail immediately climbs, switchbacking away from the trailhead only to drop suddenly to cross a washout of the drainage of Stokey Creek.
The rolling pace set in the first few hundred yards is the theme of this trail's entire length. Elevation gains and losses increase, making for a surprisingly good workout. After a long climb about a mile in, look out to your left for a nice view upriver of the mysterious Elwha valley.
Dive back into forest, where the trail continues meandering up, down and all around, through open forest set far back from the river. Notice how quiet it is. The mosses, ferns and other foliage no doubt dampen the river noise, but you're also quite far away from the river. Now free-flowing, it's cutting back and forth through the former lakebed, and is now quite far away from the Smokey Bottom trail.
After two miles of forest wandering, arrive abruptly at a dropoff, where Boulder River cascades down from its origin at Boulder Lake, five and a half miles away as the crow flies, but unreachable on trails from there.
The missing tenth of a mile on the sign at the trailhead is a mystery. A footpath heads off uphill from here, but it's certainly not 0.1 miles further to the river; you can see it right in front of you. On your way back, take time to enjoy the views of the valley and former dam site, which are arguably better on the return trip, since you're walking towards it.
WTA Pro Tip: Add on the two-mile roundtrip Glines Canyon Overlook Trail. It takes off from the same parking area, though you can also access it from the interpretive site.