Bang Saen Beach is a tourist attraction with physical characteristics of a slight slope and shallow water level. Bang Saen Beach consists of 3 beaches: Bang Saen Beach in the middle. Bang Saen Beach in the south, also known as Wonnapha Beach. And finally, Laem Thaen, which goes up to the north, is near Khao Sam Muk. Each period is considered to have a diverse ecosystem, both sandy and rocky beaches. The objective is to explore the depth of the sea floor and aquatic animal resources off the coast of Bangsaen Beach. Using a sound wave depth probe to collect data. It was found that the sea floor at Laem Thaen is deeper than at Wonnapha Beach. And the number of aquatic animal resources around Laem Taen is more abundant than at Wonpha Beach. From this study, it has been shown that the sea floor has an uneven slope and on August 9, 2023, the phenomenon of sea water changing color (Red Tide) was found and the number of plankton was found. It is very dense at a depth of about 8 meters.