This artcle gives a rough guide to scuba lessons. It is only a guide though: the scuba lessons are not exactly equivalent. Please contact your chosen diving agency for their definitive crossover requirements.


Confederation Mondiale des Activites Subaquatiques,WORLD UNDERWATER FEDERATION, Abbreviation for World Underwater Sports Federation.
CMAS is the only official diving organization recognized by the World Olympic Committee. On September 28, 1958, representatives from 11 countries including Germany, Belgium, Brazil, France, and the United States convened a conference in Brussels, dedicated to establishing an independent institution.
To cover all underwater sports.
CMAS was established at the General Assembly in Morocco in January 1959 and is currently headquartered in Italy.

CMAS leisure diving training courses include:

one-star diver course, two-star diver course, Samsung diver course, four-star diver course, one-star instructor course, two-star instructor course, Samsung instructor course, diving assistant instructor course, open water diving instructor course, international Coach qualification courses.

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is Professional Association of Diving Instructors

English abbreviation for Professional Diving Instructors Association.
Founded in 1966 by Ralf Ericssion and John Cronin.
Based on the principles of teaching, they designed a complete teaching system to quickly make diving activities flourish.
PADI is currently headquartered in Santa Ana, California, and has offices in Canada, Japan, Australia, New Zealand, the United Kingdom, Switzerland, Norway, Sweden and Singapore.

PADI leisure diving training courses include:

Open Water Diver, Advanced Open Water Diver, Emergency First Response, Rescue Diver, Master Scuba Diver, DiveMaster, Open Water Scuba Instructor, Master ScubaDiver Trainer, Instructor Development Course Staff Instructor, Master Instructor, Course Director.

The bold parts are short for divers of PADI, such as : OW、AOW、EFR、RD、MSD、DM、OWSI、MSDT、IDCStaff、MI、CD。



isNational Association of Underwater Instructors, Abbreviation of International Diving Instructors Association.
NAUI was reorganized and renamed “National Diving Patrol” by Neal Hess in the late 1950s. Based in the United States, NAUI is different from other diving organizations. It is operated by members.
The teaching principle is based on the personal experience of the coach. NAUI coaches are free to choose their own teaching content and modify the teaching according to the needs of the students.

NAUI training courses include:


is Scuba Schools International. Abbreviation for International Scuba Diving School, founded in 1970, SSI is distributed in more than 110 countries around the world, and service centers have been established in 30 regions. The textbook version is more than 30 languages.
SSI is becoming more familiar to divers with free diving teaching in mainland China.
SSI entered China relatively late, but has now become the second largest diving training institution in terms of certification.


Non-certification programs

  • Try Scuba

Entry-level scuba diving certification

In addition to the industry standard Open Water Diver (including Junior Open Water Diver for under 15s) qualification, SSI offers the following (which can be upgraded to Open Water certification with some additional training).

  • Basic Diver (ISO 11121)
  • Referral Diver
  • Indoor Diver
  • Scuba Diver (ISO 24801-1) (including Junior Scuba Diver for under 15s)

The Open Water Diver complies with Autonomous diver, ISO 24801-2. The Autonomous diver level is variously described as the best, and most popular, introductory scuba qualification.

Progression beyond Open Water

After Open Water certification, progression mainly depends on completing Scuba Specialty Programs and logging certain numbers of dives.

  • Advance Adventurer: a program of five adventure dives and an introduction to the theory of 12 specialties. Considered equivalent to PADI’s Advanced Open Water certificate.
  • Specialty Diver: automatically awarded upon completion of 12 logged dives and two specialty programs.
  • Advanced Open Water Diver: automatically awarded upon completion of 24 logged dives and four specialty programs.
  • Diver Stress & Rescue: special training to recognize and handle with stress, prevent accidents and act correctly in an emergency.Considered equivalent to PADI’s Rescue Diver program.
  • Master Diver: the highest recreational rating, automatically awarded after completing four specialties, Diver Stress and Rescue, and 50 logged dives.

Scuba specialty programs

Below are some of the speciality courses that can be completed as part of the above certifications.

  • Altitude diver – planning, procedures and equipment for diving at altitudes above 300 metres (1,000 ft) with reference to the modified decompression procedures required.
  • Boat diving – boat diving techniques, choosing a travel agency and diving operator and what equipment to take when travelling.
  • Deep diving – planning and conducting recreational dives below 18 metres (59 ft)
  • Underwater photography – introduction to underwater photography, using a digital camera system, composition and editing of underwater photos
  • Diver stress and rescue – how to avoid, recognize and deal with problems on the surface and underwater.
  • Dry suit diving – advantages of dry suit diving, types of suits, valves, underwear and accessories, dry suit diving techniques and suit maintenance
  • EAN Nitrox – planning dives with Nitrox and using Nitrox safely, including analyzing the mix before use.
  • Equipment techniques – choice of diving equipment to suit needs, and how to fit, adjust, maintain and make minor repairs to equipment.
  • Navigation – using a compass and using environmental clues, how to estimate distances, navigate search patterns, find waypoints, and return to the exit point.
  • Night and limited visibility – comparison of night and limited visibility diving, preparing for the dive, and the appropriate equipment and procedures.
  • Perfect buoyancy – understanding the principles of buoyancy control and applying them in the water to reduce diver impact on the environment.
  • Recreational sidemount diving – background, history, benefits and equipment of sidemount diving and how to configure the equipment and manage it in the water.
  • River diving – peculiarities of diving in rivers, identifying and assessing hazards an how to manage river diving equipment.
  • Science of diving – physics, physiology, decompression theory, marine life and diving equipment.
  • Search and recovery – various search patterns using ropes and compasses, planning of search and recovery operations in a team, and the correct handling of lifting bags.
  • Shark ecology – biology, ecology and identification of sharks, and procedures for diving with sharks.
  • Waves, tides and currents – basics concepts of waves, tides and currents, and suitable equipment and procedures for diving in them from the shore and from boats.
  • Wreck diving – how to get information on wrecks, to locate them, to prepare for a wreck dive, use appropriate wreck diving techniques, and identify and avoid hazards while diving on wrecks.

Freediving programs

  • Try Freediving
  • Basic Freediving
  • Freediving Level 1 & Pool
  • Freediving Level 2
  • Freediving Level 3
  • Freediving Specialty Programs such as:
    • No-Fins Freediving
    • Monofin Freediving
    • Free Immersion
    • Training Tables

Professional diving certifications

The SSI Training Standards outline the professional qualifications and progression.

  • Dive Guide (Dive leader, ISO 24801-3): prerequisites are certification for the specialities of Navigation, Deep Diving, and Night & Limited Visibility, plus Diver Stress & Rescue and 40 logged dives totaling at least 25 hours. To qualify, requires training, exams, and logging at least 50 open water dives totaling 32 hours.
  • Divemaster: awarded to certified Dive Guides completing the Science of Diving speciality and logging 60 open water dives totaling at least 40 hours.
  • Assistant Instructor (Level 1 instructor, ISO 24802-1): prerequisite Divemaster.
  • Instructor (Level 2 instructor, ISO 24802-2): prerequisite Divemaster. The qualified instructor can teach courses up to the level of Dive Guide.
  • Snorkel Instructor
  • Advanced Open Water Instructor (AOWI = OWI + 4 specialties)
  • Divemaster Instructor (DMI = AOWI + online exam)
  • Master Instructor
  • Instructor Trainer
  • Instructor Certifier

Extended Range certifications

  • XR Limited Trimix Diver
  • XR Advanced Wreck Diver
  • XR Cavern Diver

Technical Extended Range certifications

  • XR Technical Extended Range Diver
  • XR Technical Extended Range Trimix Diver
  • XR Hypoxic Trimix Diver
  • XR Technical Wreck Diver
  • XR Cave Diver
  • XR Full Cave Diver
  • XR Gas Blender

Professional certifications

  • XR Nitrox Instructor
  • XR Extended Range Instructor
  • XR Cavern Diving Instructor
  • XR Advanced Wreck Diving Instructor
  • XR Technical Extended Range Instructor
  • XR Hypoxic Trimix Diving Instructor
  • XR Technical Wreck Diving Instructor
  • XR Cave Diving Instructor
  • XR Full Cave Diving Instructor
  • XR Gas Blender Instructor
  • XR Nitrox Instructor Trainer
  • XR Extended Range Instructor Trainer
  • XR Technical Extended Range Instructor Trainer
  • XR Hypoxic Trimix Instructor Trainer
  • XR International Training Director

SSI training courses include:

Level Dives Training Free Recognition Rating
Level 1 4 Dives Open Water Course
Level 2 12 Dives 2 Specialties Specialty Diver
Level 3 24 Dives 4 Specialties Advanced Open Water
Level 4 50 Dives 4 Specialties
+ Diver Stress & Rescue
Master Diver
Level 5 100 Dives Diving Experience Century Diver
Level 6 200 Dives Diving Experience N/A
Level 7 300 Dives Diving Experience Silver Diver
Level 8 500 Dives Diving Experience Gold Diver
Level 9 1’000 Dives Diving Experience Platinum Diver
Level 10 5’000 Dives Diving Experience Platinum Pro Diver

Scuba Lessons from Different Agencies CMAS, PADI, NAUI, SSI, ADS, BSAC in 2021 5



British Sub-Aqua Club. Abbreviation of British Diving Association, established in 1953, an old British diving training institution.
Its education system is popular in the Commonwealth countries, Europe and Northeast Asia.
Its nature is similar to that of a consortium of legal persons. The profits from the organization’s operations must be used for research and development in diving safety.
BSAC developed rapidly in the United Kingdom between 1954-1955 and became the authoritative organization for policy guidance on British water sports.
It also established the BSAC Diving Training School System in 1976.
“BSAC Diving School” is an independent business group authorized by BSAC to train and grant BSAC diving qualification certification.

BSAC training courses include:

Currently, BSAC’s Asia-Pacific divisions are Japan, South Korea, and Thailand.



BSAC currently has five diver qualifications (known as grades). These are:

  • Ocean Diver: Basic skills, non-decompression diving (depth limit 20 m)
  • Sports Diver: Rescue, navigation, nitrox and decompression diving (depth limit increased to 35 m with a series of 5 m progression dives.)
  • Dive Leader: Dive leading, dive planning and management, and rescue management (depth limit increased to 50 m by completing a selection of experience dives.)
  • Advanced Diver: Fully trained diver capable of leading a group of divers in normal club activities
  • First Class Diver: Trained to lead a group of dives carrying out a project. This is nationally examined with a two-day practical test


BSAC has eight instructor grades:

  • Assistant Diving Instructor: Trained but unqualified. Must be supervised when instructing
  • Theory Instructor: Qualified to instruct unsupervised in the classroom
  • Assistant Open Water Instructor: Qualified to teach open water under supervision
  • Practical Instructor: Qualified to instruct unsupervised in open water
  • Open Water Instructor: Qualified to supervise other instructors in classroom and open water training
  • Advanced Instructor: Trained to teach advanced skills, such as boat based skills and group diving techniques
  • Instructor Trainer: Qualified to staff Instructor events
  • National Instructor: Leads Instructor Training courses and BSAC National exams

Grades no longer awarded

The following grades which are no longer awarded may still be encountered:

  • Novice I: A diver who has completed the extensive sheltered-water (i.e. pool) training of the BSAC syllabus of the time, but has not yet dived in open water.
  • Novice II: A Novice I diver who has completed two open-water assessment dives.

The distinction between Novice I and Novice II was mostly for practical reasons to do with the difference between hiring a pool and travelling to the coast. A Novice I diver would normally complete the two open-water dives as soon as possible, but if this were not possible straight away (perhaps over winter) they would at least have a specific grade within the club. The lengthy and club-oriented Novice syllabus was replaced with the Club Diver and Ocean Diver syllabuses in the late 1990s. (However, some argue the Novice description was usefully accurate and aided diver safety because nobody with such a qualification would attempt dives beyond their capabilities.)

  • Club Diver: This is more or less the same as Ocean Diver; originally the two were operated in parallel with Ocean Diver awarded at schools and Club Diver at clubs.
  • Club Instructor: An instructor grade junior to Open Water Instructor, but allowing the holder to instruct practical and theory lessons without supervision.
  • Third Class Diver: This was the entry-level grade prior to the splitting of its syllabus during the mid-1980s to create the Novice and Sports Diver grades. Divers who held this grade at the time were awarded the Sports Diver grade.
  • Second Class Diver: This was the immediate grade prior to the splitting of its syllabus during the mid-1980s to create the Dive Leader and Advanced Diver grades. Divers who held this grade at the time were awarded the Advanced Diver grade.



Association of Diving School International. International Diving School Alliance, in April 1980, on the Asagiri Plateau next to Mount Fuji, Japan, was instructed by Mochizuki to improve the quality of diving teaching, maintain the safety of students, promote the mutual aid system for emergency rescue of coaches, and the qualification certification system for teaching achievements.
The purpose is to call on senior coaches in Japan to unanimously establish a diving skill teaching and guidance group that promotes diving as the primary service business at the congress held by the local construction university hall, and name it the Japan Diving School Alliance.

ADS training courses include:

Scuba Lessons from Different Agencies CMAS, PADI, NAUI, SSI, ADS, BSAC in 2021 6



Equivalent Diving Qualifications From Different Scuba Lessons

Agency, Association, Federation Try Diving Scuba Diver Open Water Advanced Open Water Rescue Diver Advanced with Specialty Master Diver Non-pro Divemaster
UTD Open Water Diver Recreational 2 Diver Rescue Diver Recreational 3 Diver
SSI Try Scuba Diving Scuba Diver Open Water Diver Advanced Adventurer Diver Stress & Rescue Advanced Open Water Diver Master Diver Dive Guide
SNSI Open Water Diver Advanced Open Water Diver Rescue Diver
SDI Supervised Diver Open Water Scuba Diver Advance Adventure Rescue Diver Master Scuba Diver
RAID Scuba Diver Open Water Diver 20 Explorer 30 Explorer 35 Master Rescue Diver
PSS Scuba Experience Scuba Diver Open Water Diver Advanced Open Water Diver Master Scuba Diver
PSAI Open Water Sport Diver RAPID Program Rescue Diver Advanced Open Water Plus Diver
PDIC Scuba Introduction Open Water Diver Advanced Open Water Diver Level 2 DRAM Rescue Diver Advanced Open Water Diver Level 3 Master Diver
PADI Discover Scuba Diving Scuba Diver Open Water Diver Advanced Open Water Diver Rescue Diver Master Scuba Diver
NAUI Try Scuba Passport Scuba Diver Scuba Diver Advanced Scuba Diver Scuba Rescue Diver Advanced Scuba Diver Master Scuba Diver
NASE Open Water Diver Advanced Open Water Rescue Diver
NADD Scuba Experience Scuba Diver Open Water Diver Advanced Open Water Diver Rescue Diver
IDEA Introductory Scuba Basic Scuba Diver Open Water Diver Advanced Open Water Diver / 2 Stars
IDA Discover Scuba Diver Basic Diver 2 Open Water Diver / One Star Advanced Open Water Diver / 2 Stars Rescue Diving Master Diver
IANTD Open Water SCUBA Experience Supervised Diver Open Water Diver Advanced Open Water Diver Rescue Diver
IAC Open Water Diver / CMAS * Advanced Adventure Diver Dive Safety & Rescue Advanced Open Water Diver / CMAS ** Master Diver Dive Leader
CMAS Introductory SCUBA Experience / Touristic Diver One Star Diver 2 Stars Diver Rescue Diver 4 Stars Diver
BSAC Try Dive Ocean Diver Ocean Diver Ocean Diver Sports Diver Advanced Diver
ANDI Introductory Scuba Experience Open Water Sport Diver Advanced Open Water Diver Rescue Diver
ACUC Introduction or Initiation to Diving Standards Open Water Diver Advanced Diver (40m) Rescue Diver (with O2/First Aid/CPR) Underwater Guide
WRSTC Supervised Diver Open Water Diver Entry Level Rescue Diver
ISO ISO 11121 Introductory Scuba Experiences ISO 24801-1 Supervised Diver ISO 24801-2 Autonomous Diver

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