The diverse topography, geology, and unique climatic conditions have created distinctive ecosystems in this mountainous region. The diverse vegetation changes with altitude from the foothills to the summit, with a particular emphasis on dwarf forests and "mossy forests" clinging densely to the trunks of ancient trees. 
The higher you climb, the more breathtaking the scenery unfolds. From the summit of Phia Oac, you can see glimpses of the houses of the Dao, Nung, and Tay people in the distance. Far away, the Quang Thanh River meanders as if embracing the borderland with its outstretched arms. 
In winter, the spectacular natural phenomenon of the Phia Oac mountain region is the appearance of frost due to the influence of cold air masses from the North. While frost affects the lives of the highlanders, from a positive perspective, this phenomenon adds a highlight to the tourism industry. 
Many tourists constantly check the weather forecast, hoping to experience ice and snow in a tropical country. "Ice" forms on Phia Oac at altitudes of around 1,400 meters and above, while below this altitude it is bitterly cold with drizzle. Besides the frost, the area is also covered in thick fog. 
Dao Canh, a photographer living in Hanoi, shared with Heritage: “When I heard the forecast that there was a high possibility of frost in the Phia Oac mountain area, I set off immediately that night. My group traveled from Hanoi to Cao Bang at 2 AM, then took another car ride to reach the summit of Phia Oac. The temperature at that time was around -6 degrees Celsius.”
The more than 60km journey from Cao Bang city, through mountain passes to the foot of the mountains in thick fog at dawn, was also an unforgettable experience. During the exploration , he was overwhelmed with emotion when he first saw forests covered in ice, branches and blades of grass seemingly draped in a layer of ice in many different shapes and forms. 
Layers of ice, about 1-2cm thick, cling to objects, especially the "ice flowers"—thin layers of ice covering flowers, adding color to the pristine white winter landscape, creating a beautiful and romantic scene. The scenery, right here in Vietnam, feels like winter in the West.Heritage Magazine
