The Rock Islands Southern Lagoon (RISL) covers an area of 859 square kilometres and includes 445 limestone islands and 52 marine lakes surrounded by a lagoon with fringing reefs, patch reefs, and shallow water marine areas. Its lagoon is filled with hundreds of gem like “Rock Islands.” These limestone islands habitats are diverse and include marine lakes, caves, arches, tunnels, coves, forests, and wetlands, each with unique species. The RISL’s resilient reefs make it a critical area for the protection of biodiversity. The RISL supports 746 species of fish, over 385 species of corals, at least 13 species of sharks and manta rays, 7 species of giant clams and the endemic nautilus (Nautilus belauensis).