It is a National Historic Landmark and is part of the Oregon Caves Historic District within the monument.
In 2014, the protected area was expanded by about 4,000 acres (1,600 ha) and re-designated a National Monument and Preserve.
At the same time, the segment of the creek that flows through the cave was renamed for the mythological Styx and added to the National Wild and Scenic Rivers System.
Among them was Thomas Condon, professor of geology at the University of Oregon.
Guided by Davidson's brother, in 1884 he and a group of students hiked from Williams to the cavern, which they inspected by candlelight.
Activities at the park include cave touring, hiking, photography, and wildlife viewing.
One of the park trails leads through the forest to Big Tree, which at 13 feet (4.0 m) is the widest Douglas fir known in Oregon.
Oregon Caves is a solutional cave, with passages totaling about 15,000 feet (4,600 m), formed in marble.
The parent rock was originally limestone that metamorphosed to marble during the geologic processes that created the Klamath Mountains, including the Siskiyous.
Largely bypassed by the early non-native explorers, fur traders, and settlers because of its remote location, the region attracted newcomers in quantity when prospectors found gold near Jacksonville in the Rogue River valley in 1851.
Only a few people visited the cave during the next decade.
Smith made outlandish claims about the cave and its business potential, saying that it was 22 miles (35 km) long, that an ordinary horse and buggy could be driven through 10 miles (16 km) of it, that it had 600 separate chambers, and that the company planned to build something like a streetcar line from Williams to the cave.