The gulf of Tonkin is located in the east sea & Pacific Ocean, between Vietnam & China, the area is covered 126.250 km², the main gate of gulf is Con Co Island’s area in Quang Tri Province, Vietnam. The Tonkin gulf is relatively shallow (Less than 60 meters). Red River is the main river flowing into the Gulf, Hai Phong & Vinh in Nghe An are the main harbors of the gulf of Tonkin. There are Cat Ba Island, Bach Long Vi Island, Quan Lan island… these are big islands in the Tonkin gulf, Vietnam. The gulf includes Bai Tu Long bay, Lan Ha Bay, Bai Tu Long Bay…. And where is the wonderful place to explore when travelers coming to Vietnam.