taking a dive, enthusiasts must gain certification by
passing a course offered by a certified scuba diving
agency. All agencies require that participants be
proficient swimmers, in reasonably good health, and at
least 12 years old.
The course typically consists of classroom work,
practice in a pool or other confined body of water, and
dives in the open water, usually in a large lake or the
ocean. In the course, students learn to use diving
equipment, to equalize air pressure as they descend, to
swim efficiently underwater, and to ascend safely. They
also learn how to communicate underwater with hand
Scuba diving should always be practiced with at least
one other person, and partners should remain together
throughout the dive. Certification courses teach divers
the rules and advantages of the buddy system. Diving
partners learn to double-check each other's equipment,
share a single air supply, and assist one another should
a problem occur.
Controlling breathing rate is also important. During
exercises in water, diving students practice breathing
in a slow, continuous manner. Most hazards can be
avoided if divers follow the safety procedures taught in
certification courses and do not attempt dives beyond
their ability and experience.
To become certified, diving students must pass a written
exam and a swimming proficiency test, and successfully
demonstrate newly mastered skills in four open-water
dives. Proficient divers then receive a certification
card that allows them to make unsupervised dives, refill
air tanks, and buy diving equipment worldwide. Stores
that sell diving equipment and businesses that operate
diving tours require this proof of certification.