Scuba diving is mainly done for the attraction of the unattainable undersea world. It is one area of nature that mankind has not been able to fully control, we simply are not able to breathe underwater. Hence, scuba diving gives us an opportunity to be in that underwater world, even if it is just for a limited amount of time.
A scuba diver primarily moves underwater by using fins attached to the feet, but external propulsion can be provided by a diver propulsion vehicle, or a sled pulled from the surface. Other equipment includes a dive mask to improve underwater vision, a protective dive suit, equipment to control buoyancy, and equipment related to the specific circumstances and purpose of the dive. Scuba divers are trained in the procedures and skills appropriate to their level of certification by instructors affiliated to the diver certification organisations which issue these certifications. These include standard operating procedures for using the equipment and dealing with the general hazards of the underwater environment, and emergency procedures for self-help and assistance of a similarly equipped diver experiencing problems. A minimum level of fitness and health is required by most training organisations, but a higher level of fitness may be appropriate for some applications.