All PADI dive theory topics for 2023 PADI Instructor Exams

Sometimes it’s a bit confusing knowing exactly what to study:
What Dive Theory IS included on PADI Instructor Exams. 

What Dive Theory IS NOT included on PADI Instructor Exams.

All PADI dive theory topics for 2023 PADI Instructor Exams

Here we list All PADI Dive Theory subjects that you’ll find on your 2023 Instructor Exams.

A collection of all subjects, all topics, and all sub-topics. Everything right down to the last detail. 

Plus tips on how to learn everything from scratch. Make sure that you’re fully prepared.

PADI Instructor Dive Theory Step-by-Step

Together we’ll go through each of the topics and sub topics that you’ll find on the  PADI Instructor Exam.

We’ll look at each individual topic, and make sure that all areas are covered. 

I’ll give you a reason Why you should learn it.

Then I’ll give you Tips on where you can find information to fill any gaps in your knowledge.

Break it down to small chunks

It’s better if you break things down into small chunks, it makes it easier to learn.

It stops you being overwhelmed by the amount of stuff you need to learn for PADI Instructor Exams. 

It also makes it more relevant as you learn bit by bit.

Use this PADI IDC Guide as a check list

Take each subject individually and make sure that you understand it.

You can use this as a check list to make sure that you’ve got everything covered, and there are no topics that you’ve missed

PADI Dive Theory for 2023 Instructor Exams

Click on a subject and get started!

Dive Physics

We’ll start with everyone’s favourite! PHYSICS!

The sub topics are:

  • Pressures Underwater
  • Effects of Pressure
  • Pressure Volume Relationships
  • Solution of Gas in Liquid
  • Light, Heat and Sound
  • Displacement
PADI Dive Theory - Physics

PADI IDC Mock Exam papers

PLUS, you'll find lots of free videos to help.

Pressures Underwater

Why? – Understanding how to calculate pressures will give you a massive boost when it comes to calculating Effects of Pressure questions. 

It’s fundamental to answering a HUGE chunk of Physics exam questions.

Tip – Read the question.

Oh! I know that sounds corny. But I mean it.

It’s surprising how many people get these questions wrong because they didn’t look out for the words:

Gauge or Absolute, and

Fresh or Salt. 
PADI questions often confuse people. 

4 types of pressure you'll need to learn

Here are the 4 types of pressure that you need to tick off your list. 

  • Gauge Pressure in fresh water
  • Gauge Pressure in salt water
  • Absolute Pressure in fresh water
  • Absolute Pressure in salt water

YouTube video - pressures underwater

You can learn all about pressure on my video here

Effects of Pressure

Why? –  This takes up so many areas of a Physics Exam. 

Tip – Take a look at my “Box Method” video on my Physics page

It makes all of these questions much easier.

Some people think that these  subjects are stand alone topics. 

  • Boyles Law
  • Partial Pressures
  • How much a diver breathes at different depths
  • Density

But the truth is that they all have the same calculation.

You simply either multiply or divide the subject by the absolute pressure. 

In essence, all of these subjects are the same.

YouTube video - Effects of pressure

You can learn all about Effects of pressure questions here:

Pressure Volume Relationships

Why? – This is so fundamental. It’s on the very first lesson that an Open Water diver learns.

Tip – Watch my video about Pressure Volume Relationships on my By me a Coffee site

Essentially this is the same as calculating Effects of Pressure. 

However it’s a good idea to understand the relationship between Pressure and Volume. 

Solution of Gas in Liquid

Why? – This is Henry’s Law. 
Not only is this a Physics subject, but it’s also a Physiology subject. It’s the cause of Decompression Illness. 

Tip – You guessed it! I have a video about Henry’s Law!

Light, Heat and Sound

Why? – As a Dive Professional, it’s a good idea to be familiar with all of these. 
Not only to pass exams, but all of your future divers will be affected by Light, Heat and Sound at some time during their training. 

Tip – People get confused by the difference between Heat and Sound underwater. 

Heat is 20 times faster underwater than in air. 

Sound travels 4 times faster.

So, find a way to help you remember. 
Like H20 is water. the H could be Heat, and 20 would be the speed. 

Find something that works for you. 


Why? – This is a new ground for Divemasters who want to become PADI Instructors. 

You won’t have seen any Displacement questions until you start to study for you PADI IDC.

Tip – I cover this topic on my Physics page

There’s a video there too! 

YouTube video - Displacement

It’s quite a big subject, but it’s all explained in this video on displacement


The Physiology section is simple once it’s broken down into smaller parts.

Breathing (Respiration) and Decompression Illness make up the lion’s share of Physiology exams. 

PADI dive theory phyiology


Why? – Breathing covers all Lung related questions: It’s a broad subject with questions about:

  • Oxygen
  • Carbon Dioxide
  • Overexertion
  • Mammalian reflex
  • Dead air space
  • Shallow Water Blackout

Phew! it looks a lot!

Tip – The good news is that ALL of this is explained in a Respiration Video

Decompression Illness

Why? – Decompression Illness covers PADI Instructor Exam questions on:

Decompression Sickness (DCS) &

Lung over-expansion injuries.


Tip – All explained in this DCI video

Other Physiology topics

Why? – You might find questions taken from many smaller areas to do with Physiology:

  • Ears
  • Narcosis
  • Stress

and some from First Aid subjects: 

  • Heat Stroke
  • Heat Exhaustion
  • Carbon Monoxide poisoning 
  • Carotid sinus reflex

Tip – I don’t have any FREE stuff to help with these subjects, but EVERTHING is covered in my FULL PADI IDC PREPARATION COURSE.

(videos, theory, standards questions, mock exams, teaching tips in class and pool, loads more!)

Otherwise, you can find information in your encylopeadia, or just google the subjects.


You’ve probably only dived using a computer up until now.
But all PADI Professionals need to know how to use the PADI dive tables. 

Once you get used to RDP questions, they’re fairly easy. 

You just need a bit of practice. 

PADI Dive Theory for Instructors

PADI IDC Mock Exam papers

PLUS, you'll find lots of free videos to help.

PADI RDP background and Rules

Why? – Mostly, these are the questions about flying after diving, or what to do if you miss a safety stop. 

Tip – Almost all of the answers are right in front of you. Either on the table itself, or on the “Rules” tab of your PADI eRDPml.

How to use RDP, and eRDPml.

Why? – These are the bulk of the RDP questions. 
The types of questions where you have to work out pressure groups or minimum surface intervals etc. 

Video: How to use PADI eRDPml

Tip – I have a video that will help. It’s here. It explains how to use all functions of the eRDPml. 


The equipment exam is largely made up of only two subjects: 

  • Regulators
  • Cylinders
Become a Scuba Instructor


Why? – Lots of Instructor Exam questions are based on Regulators: 

  • 1st Stage 
  • 2nd Stage
  • Upstream
  • Downstream
  • Intermediate Pressure
  • Pilot Valves
    … oh and it goes on!

Tip – Good news!
It’s all broken down in simple terms in this video on my Buy me a Coffee site.


Why? – You’ll need to be able to answer questions about steel and aluminium cylinders. 

Tip – There is a lot of information about exam topics on Cylinders on my PADI IDC theory – Equipment page.

Other Equipment topics

Why? – You will need to be familiar with other equipment topics, such as:

  • SMBs
  • Lifting bags
  • Neck seals
  • Dry suits

Tip – you can find valuable information by googling these topics, or you can find everything you need to know in order to pass your PADI Instructor Exam on my 
Complete PADI Preparation Course.

Diving Skills and the Environment

This subject neatly falls into two categories. 
You’ve guessed it!

1. Diving Skills. 
2. Environment.


Diving Skills

Why? – You need to be able to answer questions on some skills. 

  • Emergency Weight Drop
  • CESA
  • Alternate Air Source
  • Signals (especially night dive)

Tip – Take a look in your Guide to Teaching manual, and your Instructor Manual.

The Environment

Why? – These are the questions about:

  • Rip currents
  • Shore Diving
  • Up-welling/Down-welling
  • Navigation
  • Search Patterns


Tip – Google, encyclopedia, or your manuals.
OR EVERYTHING on this page is neatly packaged in my Online Courses.

PADI Dive Theory for Instructors

I hope that this helps you to find out exactly what and where you’ll find the right information to help with your studies.  

Here are some PADI IDC questions that you can test your knowledge.

1. FREE videos for PADI Dive Theory

Lots of help here. 

Physics, Physiology etc.

All the main suspects!!

All of these videos are taken from my Online Preparation course. 
But of course you get to see them for FREE. 

Take a look! 
There’s a lot there. Naturally not ALL of my course videos are here, but certainly a lot are. 
And of course if you find them useful, you might want to buy me a coffee to say thanks! 
I’d really appreciate that.

I’d appreciate it even more if you had something nice to say in the comments! 

Click here for Free videos

2. Mock Exam Papers

Ok, you have to pay for these. 

(But not much!) They’re right up to date, so you’ll have to use your 2023 PADI Instructor Manual to find the newest PADI standards. 
It’s SO important for you to practice with realistic and up to date questions. 

Practice, Practice and then Practice some more! 
This is True Dive Theory for PADI Instructors!

PADI IDC Exam Questions - Mock Exams

You can buy some realistic 2023 PADI Mock Exam papers. 
They’re all written with the same format and the same content as you’ll find on your final PADI Instructor Exams. 

Each individual exam (A, B, C, D or E) is a replica of what you’ll find on your final PADI Instructor Exam. 
Each has

  • 5  Theory Exams each with 12 questions
  • 1 Standards Exam with 50 questions

And of course all of the answers.

Buy each exam separately for US$12 each (or the equivalent in your currency)

Click HERE for ALL FIVE mock exam papers for US$49 (or equivalent in your currency)

3. PADI Dive Theory for Instructors Online Course

Most people find this the best option,  when it comes to mastering Theory and Standards exams.

Dive Theory and Standards Preparation Course

This online course is perfect for you.

  • Explained in simple terms.
  • Jargon Busting sections!
  • Lots of practice exams.
  • Videos (not taught in the “PADI” way!)
  • Quizzes to help you understand.
  • The most “up to date” questions.
  • Standards questions based on 2023 PADI Instructor Exam.
  • All Standards exam questions found in 2023 version of PADI Instructor Manual.

If you have found traditional teaching difficult to understand, then this course is for you.

It’s packed with simple videos and quizzes to help you with any subjects that you find difficult.

I explain things in very simple terms. I try to break through the “jargon” and also give tips on how you can pass this information over to others. 

The Online Theory Preparation Course


All of the videos are here, followed by questions to check that you’ve understood.

Then of course ALL of the above mock exams are included. 

Plus LOTS more! 

Take a quick look at what’s inside

Dive Theory

Enrol here: click on picture
US$ 79 (or equivalent)

That's it for now!

I hope that you’ve found this helpful. 

I know that you’ll be successful as long as you take your time, and find the right way for you to learn. 

More information:

There are another couple of articles that might help. 
One is: 
Prepare for your PADI IDC  It’s a guide for people who struggle a bit with dive theory. 
Another article here: 
12 top reasons why you should prepare for your PADI IDC. 

Last modified: 10th January 2023
Author: Steve Prior