How scuba certification courses are structured

What certification is

A certification card, often called a C-card, is issued by a training agency after an instructor signs off that you met every requirement of a course. Dive centers usually ask to see it before they fill a cylinder for you, rent you gear or take you on a guided dive. It is less like a license and more like proof of training: it says what you were trained to do, where and how deep.

There are several international training agencies, plus national bodies and clubs in some countries. Their entry-level courses differ in name and detail, but they share the same structure and teach the same core skills. This site doesn't recommend any agency. Your instructor will give you the materials for the course you take, and those materials are the authority on the details.

The three parts

1. Part 1

   Theory

   Online, a book or a classroom

   How pressure affects your body and your air, how gear works, how to plan a dive and handle problems.

   Ends with quizzes and a final exam

   More on theory

2. Part 2

   Pool

   A pool or calm, shallow water

   Your first breaths underwater, then skills such as clearing a flooded mask and sharing air, repeated until they feel routine.

   Ends when every skill is done to standard

   More on pool

3. Part 3

   Open water

   A lake, quarry or the sea

   Usually about four dives over at least two days, where you repeat the pool skills in real conditions with an instructor.

   Ends with your certification card

   More on open water

Theory

The knowledge part explains what happens to your body and your air under pressure, how the equipment works, how to plan a dive and what to do when something goes wrong. Many courses offer it as e-learning, with short chapters, quizzes and a final exam. Others use a book, videos or classroom sessions. Read more on the theory part of a course.

Pool or confined water

You take your first breaths underwater in a pool or in calm water that is shallow enough to stand up in or close to it. The instructor demonstrates each skill, you copy it, and you repeat it until it feels natural. See pool and confined water skills.

Open water dives

The course finishes with a series of training dives in open water, usually about four spread over at least two days. You repeat the pool skills in real conditions and start to dive the way you will after the course. See open water training dives.

Before you start

• A medical questionnaire. Every school will ask you to complete one. Some answers mean a doctor has to review it and sign off before you go in the water. See fitness to dive.
• Water comfort. Expect a swim and a float test. The distance and method vary, so ask the school.
• A minimum age. Agencies set their own, and younger divers usually get a junior card with extra limits.
• Time. A first course commonly takes a few days of in-water training, plus however long the theory takes you. Some people spread it over several weekends.

Splitting a course between places

Many agencies let you finish the theory and pool training at one dive center and complete the open water dives at another, often somewhere you are traveling to. It is usually called a referral. If you plan to do this, ask both schools how they handle the paperwork and how long the first part stays valid.

What the card lets you do

An entry-level card usually certifies you to dive with a buddy of similar or higher training, without an instructor, in conditions similar to those you trained in. Many first certifications advise staying above about 18 to 20 m (60 to 66 ft). The exact limit is set by the course you took, so check your own materials and card. Some first courses are more limited and certify you to dive only with a dive professional.

The card doesn't make you ready for every kind of diving. Strong currents, cold or dark water, caves, the inside of wrecks and deep dives all need more training and experience. The dive safety guide explains why.

Certification FAQ