Lewis and Clark Caverns, one of the largest limestone caverns in the Pacific Northwest, is also Montana's oldest state park, and one of its most elaborately developed, with a visitor center, interpretive displays, and cabin and tipi rentals. Shower facilities, an amphitheater, food concession, gift shop, educational programs and guided tours are available during the summer months.
The 2,920-acre park accommodates activities from hunting to hiking, and provides foot access to the Jefferson River, but the star attraction is the cavern itself. The 160-acre underground site was discovered in 1892, and declared a national monument in 1908, though the cavern wasn't fully surveyed until 1911. Improvements to open the caverns to tourists were accomplished largely by the Civilian Conservation Corp during President Franklin Roosevelt's New Deal. The caverns were transferred to state management in 1937, and opened as Montana's first state park in 1941.
Lewis and Clark never actually saw the caverns, which take their name from the fact that the site overlooks about 50 miles of the explorers' route along the adjacent Jefferson River.
The caverns, decorated with colorful stalactites, stalagmites, columns, and helictites, were formed by the dissolving action of acidic groundwater percolating through beds of Madison Limestone during the ice ages. Now lit and traversed with staircases and walkways, the caverns offer an accessible underground wonder, and a unique challenge for photographers. Schedule about two hours for the tour.