北部湾位于我国广西南部,是一个三面靠陆的半封闭内陆海,湾内水深小于100米,其等深线的分布趋势大致与海岸线平行。海底地形由北向南倾斜,深度沿岸较浅向湾口逐渐加深,平均深度约为38米。湾口与南海相连,宽约130海里,深度较大,是与外海水交换的要道。湾东尚有琼州海峡与广州湾沟通,但其宽度很窄,深度也不大。从整个湾形来看,它极类似一个“扇形”海区(图1)。 Beibu Bay is located in the southern part of Guangxi of our country. It is a semi-enclosed inland sea on three sides. The water depth of the bay is less than 100 meters. Its isobath is roughly parallel to the coastline. The seafloor topography slopes from north to south, with a shallow depth going deeper toward the mouth of the bay with an average depth of about 38 meters. Bayou and the South China Sea is connected to a width of 130 nautical miles, a greater depth, with the exchange of arteries. Bay East still Qiongzhou Strait and Guangzhou Bay communication, but its width is very narrow, the depth is not large. From the perspective of the entire bay, it resembles a “fan-shaped” sea area (Figure 1).