Antelope Canyon may be the most striking slot canyon. A slot canyon is a narrow canyon sliced through a mesa by the forces of nature. Some canyons measure < a yard across at the top, but drop 100 feet or more from the rim to the bottom.
The Wishing Well glows blue-green at Luray Caverns, Virginia; originally called Luray Cave, which is a large commercial cave just west of Luray, Virginia, USA. Discovered in the Caverns are in the Shenandoah Valley just east of the Allegheny Range