Lyman Run Lake is a 45-acre impoundment sitting in the floor of a steep hardwood valley in Potter County, seven miles west of Galeton and fifteen miles east of Coudersport. The 595-acre state park around it is almost entirely ringed by Susquehannock State Forest, so the view from the water is ridgeline in nearly every direction and very little else. Swimming happens at a sand beach about 300 feet long on the northeast shore, a short walk from the day-use parking off Lyman Run Road.

The beach opens the Friday before Memorial Day and runs through mid-September, 8:00 AM to sunset. There is no lifeguard. Pennsylvania stopped staffing this beach in 2008, and it has been swim at your own risk ever since, with the posted rules at the water's edge as the only supervision. Entry costs nothing. Pennsylvania charges no admission or day-use fee at any of its state parks, so the beach, the parking and the picnic area are all free. The bathhouse has flush toilets and changing rooms, and a seasonal concession sells food and rents boats. Dogs are barred from the sand and from the swimming area, and the beach is smoke-free, e-cigarettes included, with designated smoking spots just off it.

Look across the water from the beach and the stepped concrete spillway at the east end is the newest thing in the valley. The original 1949 earth-fill dam, 920 feet long and 50 feet high, was judged unsafe after roughly fifty years, drained, breached for inspection, then replaced outright with a roller-compacted concrete structure. The lake that came back is cold and clear, and DCNR singles out its water quality. That shows up in the fishing: trout, smallmouth bass and panfish in the lake, with stocked trout in Lyman Run below the dam.

Boat traffic stays quiet because the lake allows electric trolling motors only, at no-wake speed. There is a launch ramp, a courtesy dock and a mooring area holding 60 boats, with mooring permits sold at the park office. Paddling the full shoreline is an easy afternoon.

Camping is on site in two areas totaling 35 sites, 29 of them with electricity and four walk-to. Daggett Campground runs from the first weekend in April into late October and has modern restrooms. Lower Campground stays open to the end of deer season and uses composting toilets. Both have hot showers. Lower also connects directly to the 43-mile Susquehannock ATV trail system, which is worth knowing in both directions, since summer weekends bring machine noise to that end of the park.

About 4.1 miles of trail lie inside the park boundary, 6.5 miles counting the stretches that run out into the state forest. Rock Run Trail climbs to a vista looking down on the lake. Lyman Run Trail follows an old railroad grade the length of the park, but hikers between Lower Campground and the spillway have to ford the creek, so count on wet feet.

The other draw here is overhead. Cherry Springs State Park, Pennsylvania's first designated Dark Sky Park, is 7.1 miles away and is administered out of the Lyman Run office at 454 Lyman Run Road. Plenty of people swim in the afternoon and drive up for the sky after dark.