Sequoia National Park's majestic, towering forests will have definitely have visitors looking skyward at the big trees, but don't forget to look down, too. One of 270 caves hidden throughout the park, Crystal Cave offers visitors a remarkable peek beneath the surface of the Sierras. Formed of marble, Crystal Cave in California’s Sequoia National Park is decorated with curtains of icicle-like stalactites and mounds of stalagmites. This spectacular cave was first discovered by Sequoia National Park employees in 1918, and has been one of the area's primary visitor attractions since public tours were first offered in 1941. Special LED lighting allows visitors to better see fossils, rare minerals and subterranean species without harming this marvelous underground wonder. To reach it, you must drive to the end of the twisting, seven-mile road heading west from the General’s Highway, two miles south of the Moro Rock turnoff. The Sequoia Parks Conservancy offers guided tours of Crystal Cave from about Memorial Day to mid-October, depending on weather. Cave temperature is a constant 48 degrees, so bring a sweater and take a trip back in time! Tickets are not sold at Crystal Cave; purchase them in advance at www.recreation.gov.