The mountainous zone can be divided into two parts: the eastern mountainous region extending from Tien Yen through Binh Lieu, Hai Ha, Dam Ha and Mong Cai; and the western zone ranging from Tien Yen through Ba Che and Hoanh Bo, north of Uong Bi Town. The former is a continuation of the Thâp Van Dai Son range in China. There are two main chains: Quang Nam Chau 1,507 m and Cao Xiem 1,330 m. The western zone features smooth and curved mountains called Dong Trieu with Yen Tu Mount 1,068 m in Uong Bi region and Am Vap Mount 1,094 m in Hoanh Bo District.
The midland and coastal plains include a low range of hills weathered by both wind and water; forming fields and river basins. They include the zones of Dong Trieu, Uong Bi, northern Quang Yen, southern Tien Yen, Dam Hà, Hai Ha and some of Mong Cai. In the estuaries, alluvial soil is deposited, creating low tidal flats. This can be found in the areas of southern Uong Bi, southern Quang Yen (Hà Nam Island), eastern Quang Yen, Dong Rui (Tien Yen), southern Dam Ha and Mong Cai, southeastern Hai Ha. The midlands and plains of the coastline are extremely favourable for agriculture and transport. It has become a densely populated area of the province.
The sea and island zone of Quang Ninh has a unique terrain. There are more than 2,000 islands, making up two thirds of the country’s islands. They extend along the coast for more than 250 km and divide into numerous layers. The largest islands are Cai Bau and Ban Sen, while the smallest are just like rocks in a garden. Van Don and Co To are island districts. There are thousand of islands on Ha Long Bay and Bai Tu Long Bay, many of which contain caves. Besides areas of alluvial deposits, there are also white sand zones which have built up from tidal action. Some places have formed white sand mines producing materials for the glass industry (Van Hai), or have developed into wonderful tourism spots (Tra Co, Quan Lan, Minh Chau, Ngoc Vung).
The sea bottom terrain of Quang Ninh isn't smooth, and has an average depth of 20 m. There are the remnants of ancient streams and underwater rocky banks. The streams from the mainland connect to deep drains along the sea-floor; creating a series of waterways, canals and harbours along the coast./.
