Columbia Reef is a scuba diving site located off the coast of Cozumel, Mexico. It is a popular site for both experienced and beginner divers, due to its shallow depth and clear visibility. The reef is home to a variety of marine life, including tropical fish, sea turtles, and coral formations. Columbia Reef is a large wall reef that runs parallel to the coast of Cozumel. The reef is about 1 mile (1.6 km) long and 0.5 miles (0.8 km) wide. The top of the reef is about 30 feet (9 m) below the surface, and the bottom slopes down to about 100 feet (30 m). The reef is made up of a variety of coral formations, including staghorn coral, elkhorn coral, and brain coral. The reef is also home to a variety of marine life, including tropical fish, sea turtles, stingrays, and sharks.