Underwater diving, also known as scuba diving, is a popular activity enjoyed by many around the world. There are numerous synonyms that can be used to describe this activity based on different aspects of the experience. For example, "deep-sea diving" is often used to describe diving at depths greater than 18 meters. "Free diving" refers to diving without scuba gear, while "snorkeling" is a type of diving that involves swimming on the surface while wearing a mask and snorkel. "Recreational diving" is a term used for non-professional diving activities and is often contrasted with "technical diving" which is more complex and demanding. The use of different synonyms helps to capture the diversity and nuances of underwater diving within language.