Lake houses in Raystown Lake

Manmade Raystown Lake, which sprawls more than 8,000 acres, is the biggest lake that resides entirely inside the state of Pennsylvania. (There are larger ones that spill beyond the state’s borders.) It was built by the Army Corps of Engineers, which still owns much of the surrounding land, meaning it has gone largely undeveloped. This big, serene body of water looks out to verdant hills and, in the distance, the Allegheny Mountains, and not much else. Vacationers come here to swim, boat, scuba dive, and fish, or to wander the forested trails nearby. Nestled in the Central Pennsylvania countryside, this place is all about rural idyll and outdoor recreation, with side trips to charming towns that seem preserved in a bygone era, replete with drive-in movie theaters and homegrown museums. But this place has a little mystery, too: Since 1962, people have reported seeing an unusual creature in the lake that locals affectionately call Raystown Ray.

Summer is the high season here, when fun on the lakefront is at its peak. Late spring and early fall also make for pleasant times on the water, especially during leaf-peeping season, when the trees put on a show with orange, red, and gold leaves. In the winter, things slow down considerably. Some restaurants close up shop for the season, and some attractions are open by appointment only, so check ahead if you’re planning a cold-weather stay.

Lincoln Caverns

Explore two big caverns here, filled with sparkly crystals, jagged stalactites, and crenulated flowstones. At night you can take a blacklight tour, for a chance to see the phosphorescent rock formations lit up in ethereal shades of blue and purple. On Wednesdays there are workshops for curious visitors on topics such as bats and gemstones. The caves are open by appointment only during the winter months.

Isett Heritage Museum

Melvin Isett has amassed antiques and memorabilia for decades, with the goal of opening a museum, and this eclectic 40,000-piece collection is the result. In three large buildings, including a circa-1940s renovated barn, you’ll find sprawling displays of Victrola record players and 8-track-tape players; antique printing presses; laundry, medical, and dental equipment; fainting couches; fireplaces; and an ice cream fountain from the dairy where Isett worked as a teenager. It’s difficult to say exactly what the theme of this museum is, or whether it has one. One thing is certain: It is not boring.

Rockhill Trolley Museum

Go for a ride on a vintage trolley car at this museum dedicated to preserving the golden age of trolley travel. Its collection of more than 30 vehicles includes streamlined passenger trolleys painted in jolly colors, snow sweepers, and cargo haulers, some from international origins such as Brazil and Portugal. Many are in operation, and volunteer conductors take passengers on two-to-three-hour scenic rides.