The sandy island of Bazaruto, Mozambique, is located approximately 50 miles (80 kilometers) southeast of the mouth of the Save River. The warm, southward-flowing Mozambique Current seems to contribute to the increasing buildup of the sandy coastline. Because the water along this coastal area is very clear, much of the subsurface channel pattern around the island is discernible. Several narrow lines of plankton bloom (barely visible in the photograph) parallel the shoreline. The coastal plains show numerous lakes and a swampy environment that appears to be karst topography. Underlying the area is limestone rock that has eroded into a pockmarked landscape, creating water-filled sinkholes. Rainfall amounts in this humid equatorial climate range between 20 and 40 inches (50 and 100 centimeters) annually.