A snorkeling site is a great place to explore the underwater world. It can be a REEF, SHOAL, LAGOON, or coral REEF. A REEF is an underwater structure made of rock, coral, or sand. A SHOAL is a shallow area of water with sand or gravel on the bottom. A LAGOON is a shallow body of water separated from the sea by a barrier island or REEF. A coral REEF is an underwater ecosystem composed of coral, algae, and other organisms. All of these sites provide a unique and exciting experience for snorkelers.