Likely to flood during heavy rain season. Likely to find levees and bayous in such areas. Now we're looking at a piece of the coast. What we see here is differences in water depth and material suspended in the water. The material comes from the rivers.
Rivers come out of the mountains carrying lots of material.
As river water meets ocean that material is deposited. It drops out of the water. The heaviest material, sand, drops out first. Lighter material drops out later. We also have a current running from the bottom of the image to the top right corner.