A scuba is a portable breathing device for deep sea divers. With the help of a scuba tank, divers can explore very deep parts of the ocean.
You can use scuba for the compressed air tank itself, or to describe the divers who use it — scuba divers. Most of these scuba divers use masks and wear rubber fins on their feet to propel themselves through the water. Scuba devices are useful for recreation and tasks like coast guard search and rescue operations or marine biology observations. Scuba is an acronym, standing for "self-contained underwater breathing apparatus."