Angel Eye Mountain
Angel Eye Mountain (Nui Mat Than) is a distinctive karst mountain in Quoc Toan Commune, Tra Linh District, Cao Bang Province, within the UNESCO Non Nuoc Cao Bang Geopark. It is notable for a large circular hole about 50 meters in diameter piercing the summit, resembling an eye. Surrounded by a grassy valley and seasonal lakes, the mountain is a prominent natural landmark and photography site in northeastern Vietnam.