Snorkeling
Generally, people snorkel in shallow reefs ranging from sea level to 4 meters (13 feet) deep. Snorkelers can also explore deep water reefs.  However, to see deeper reefs, a snorkeler has to hold their breath and dive down to the reef to see it. This kind of snorkeling takes more skill and fitness than shallow water snorkeling. It is also more dangerous than shallow water snorkeling.