The results of both studies BEIBU and PECAI were obtained in the Beibu Gulf also known as Gulf of Tonkin (GoT) and the Pearl River Estuary (PRE). The map presents the regional setting of the studies. Marked are the Red River Delta (RRD), LP (Leizhou Peninsula), the Hainan Island (HI) and Qiongzhou Strait (QS). The bathymetry in 5 m increments is color labeled as described in the legend and based on ETOPO1, whereas the topography is based on SRTM90. Isobath in 25 m increments are also indicated (thin black lines). The chart was created by M. Endler (IOW).