Many beautiful natural scenes are at Phia Oac because at this place, it is a very unique climate. In some years in the past, even, there is no place in Vietnam happened with snow down, but this phenomenon occurs in Phia Oac. The ice has killed many plants, but it also made many other species became more sustainable with such harsh conditions. Pass belongs to the territory of the three communes (Thanh Cong, Quang Thanh, Phan Thanh) and the Tinh Tuc town (Nguyen Binh District - Cao Bang Province). Forest in Phia Oac is very special; and it is the high valuable heritage inventory of Northeast. With altitude is 1931m in comparison with the sea level, it higher than some travel destinations as Sa Pa and Tam Dao towns is 450m; and it is higher than Ba Vi nearly 1000m. Thus, it is enough to become the most prominent place in the Cao Bang province in particular, and in Northeastern Vietnam in general.
Phia Oac attracts visitors because it has a lyrical landscape of the forests of this type with places such as the conservation areas, the national parks; it includes of an area is more than 300000ha. Besides, there is a large-scale salmon farming here. Phia Oac is the source of 5 major rivers in the area, including the Bang and Hien rivers. Water flow from the rivers and mountains of the Phia Oac forest is plentiful. That is the source of the endless energy for the Ta Sa hydro. There is a path, which is longer than ten kilometers from the Phia Den destination up to the top of the Phia Oac pass (the highest) is known; it is twisting all around; many bends are very protruding and seem to want to throw everything down the deep chasms. However, if we go up higher, the landscape is spectacular and spread out. It is immense to make sense of the people seemed lost in a place like "fairy on the road". And then, everyone breathes to make the tight chest. There are the old trees, which stand among the blue-violet bamboo forests in the light of slight afternoon sun; it is still cold. There are the vertical special green casuarina-forests, which are very large; they extend from the valley to the top of the pass. Actually, it collects on the eyes with special features of these forests.
Phia Oac in the past was wild with the horror stories of a poisonous sacred forest area . Nearly a century ago, the French came here to explore and create the value of this place. With the French, which participate in building the pass, Colia is called to demonstrate the presence of many people have paved the way through the mountainous wilderness. The reason which is called as above because here, there is a female engineer, who involved in designing the pass, had died in the attack of a lion. Since then, they call this mountain pass in the name of the woman engineer with Colia to commemorate and remember the land is beautiful but wild. After completion of the road through the land of "the little fairy", The French also built the resorts; the villas were built with the stones; and there the pit system was used for mining tin throughout the mountains. It stretched for several kilometers. The villas here have been abandoned for many years, but they still conserve the shapes. These forms are for people can imagine the old French architecture of the past.
