Scuba Theory for Pro's and Dive Die-hards: Pass any exam

The Dive Environment, Physics, Equipment, Physiology and Decompression Theory made easy, and all you need to know.
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  • Lectures 36
  • Length 3 hours
  • Skill Level All Levels
  • Languages English
  • Includes Lifetime access
    30 day money back guarantee!
    Available on iOS and Android
    Certificate of Completion
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About This Course

Published 8/2015 English

Course Description

We have designed this course for divers training to be dive guides and dive instructors, but all divers can gain a lot from learning more about the diving environment, the physics of diving, dive equipment, the physiology of diving and decompression theory. You need no prior knowledge to do this course. This dive theory course consists 5 sections with in total 35 lessons: 13 small text lessons and 22 video's (two and a half hours of video in total) and a quiz after each section. There is extra material to practice, and we included many informative links to sites and video's that deal more in depth with the subject. This is a complete dive theory course, and it will take around 15 hours to complete it. It is the ideal way to prepare for theory exams for dive professionals, or to get to know the theory behind your hobby.

We hope you will enjoy learning about the thing you love: diving. We designed this course to help you understand what is happening and why it happens before, during, and after a dive. Many of you will be preparing for an exam to become a dive professional. This course tells you all you need to know. You need no specific software or prior knowledge to follow this course. You do need a calculator for the physics section, and of course you must be interested in diving!

What are the requirements?

  • You need no specific software or prior knowledge to follow this course.
  • You will need a calculator for the Physics section.

What am I going to get from this course?

  • Prepare for your dive theory exams the easy way. Learn all you need to know about the theory of scuba diving. In this course, we bring you the easy way up to the level where you will confidentely pass the theory part of the exams of the most important dive organisations, either to guide dives or to teach diving. Master effortlessly (well, allmost): The Dive Environment, the Physics of Diving, Equipment, the Physiology of Diving and Decompression Theory.

Who is the target audience?

  • Scuba divers taking professional level dive courses: dive guide and instructor courses (any organisation).
  • Current dive guides and instructors who want to refresh their knowledge of scuba diving theory (any organisation).
  • Serious divers who want to learn more about the diving environment.

What you get with this course?

Not for you? No problem.
30 day money back guarantee.

Forever yours.
Lifetime access.

Learn on the go.
Desktop, iOS and Android.

Get rewarded.
Certificate of completion.


Section 1: Welcome

Welcome to your quick journey into dive theory country. We hope you will enjoy learning about the thing you love: diving. We designed this course to help you understand things that happen in the diving environment, and what's more, why these things happen. Many of you will be preparing for an exam to become a dive professional. This course is basically all you need to know.

We will start off easy with a short introduction to the dive environment, where we look at tides,currents, waves, coasts, ecosystems. Why are there usually two tides per day, but only one moon? Why do currents follow a certain pattern over the globe? What makes waves big, how do they break at the beach? How many different types of coasts are there, and why? How do marine biologists talk about the marine life they study and describe?

Next, we go on with the physics of diving. We will keep the numbers to a minimum, and we promise: no formulas. We will show you how to use your experience as a diver and your common sense to understand and calculate everything. If you had a fear of physics and calculations, as we know many of you have, we will cure you from it. Give it a go. You will calculate buoyancy, air consumptions, pressures, partial pressures with a smile on your face. Well, perhaps that is too much to ask. Without sweating, let's settle for that.

Next, we have a look at equipment, but because manufactures can give you so much more information than we can, and because we know you love shopping or looking at brochures, we keep it to the minimum. We tell you about tanks and tank maintenance, burst disks, balanced and unbalanced regulators, venture valves, pilot valves, up-stream and down-stream valves, and types of depth gauges.

After this, we are ready to understand what happens in your body when you go diving. In the physiology of diving, we will have a look at blood, hearts, lungs, ears, and all the things that can go wrong. More importantly, we will give you the knowledge you need to respond when things go wrong, and, more importantly, how to avoid things going wrong. That does not mean you won't need an Emergency First Responder course. You do, because you need skills and practice. But you will know all you need to know.

Last we can bring it all together, and we explain to you exactly how decompression theory works. You will know how compartments, half times, M-values are used to make models for your tables or computers to keep you safe.

The most important things you must get in your head is: this supposed to be fun. Forget whatever bad experiences you had with bad teachers, bad courses and bad books, studying subjects you did not care about. This is different. You DO care about what you are doing here. You WANT to know the things in this course.

What am I going to learn on this course?
2 questions
Section 2: The Diving Environment

How the Sun and Moon cause tides. Spring tides, neap tides, and the three patterns of tides on earth caused by the rotation of Earth and local topographical features: Diurnal, Semi-Diurnal and Mixed tides.


Currents are caused by tides, global wind patterns, and upwellings. Big currents, called gyres, go clockwise on the Northern Hemisphere, and counter-clockwise on the Southern Hemisphere because of the Coriolis effect.


There are primary coasts, made by processes of the land, and secondary coasts, made by processes of the ocean.


Waves:height, length, frequency and propagation. Ripples, Seas and Swells. The fetch and a fully developed sea. The surf.


The Benthic, the Pelagic, the Euphotic, the Disphotic and the Aphotic zone. Ecosystems and the food pyramid/food webs. Species, Populations, Communities, and Habitats. Producers, Herbivores, Carnivores and Decomposers. Symbiosis: Mutualism, Commensalism and Parasitism.

The Diving Environment
10 questions
Section 3: The Physics of Diving

Heat: Conduction, Convection, Radiation.


Refraction, Absorption, Diffusion and visual reversion.


Sound goes four times faster underwater, direction cannot be determined, but intensity can be.


The pressure of water: sea water: 1 bar per 10 meters, fresh water 1 bar per 10.3 meters. Ambient pressure and gauge pressure. The password for the extra exercises is divetheoryiseasy.

The Relationship of Pressure to the Volume and Density of a Gas (Boyle's Law)

Calculate volume, density and air consumption by multiplying or dividing with the ambient pressure.The password for the extra exercises is divetheoryiseasy.


Calculate air consumption at different depths by multiplying or dividing with the ambient pressure. The password for the extra exercises is divetheoryiseasy.


Air consists of 79% Nitrogen and 21% Oxygen. This means at one Bar, the partial pressure of Nitrogen is 0.79 bar, and of Oxygen 0.21 Bar (Dalton's law). The password for the extra exercises is divetheoryiseasy.


# text


Saturation, Super saturation, Excessive Super saturation and bubble formation.


Weight pulls down, buoyancy pushes up. Buoyancy equals the volume of the displaced water divided by the weight of the water per litre. Fresh water: 1 litre, I kg, Sea water, 1 litre, 1.03 kg. The password for the extra exercises is divetheoryiseasy.

The Physics of Diving
10 questions
Section 4: Diving Equipment

Steel and aluminium tanks. Burst disks. Visual inspections and hydrostatic tests. K-valves, DIN valves, and J valves. Tank markings.


The first stage and the second stage. Balanced and unbalanced. Environmental seals. Fail safe designs, upstream and downstream. The Venturi system.

Dive Equipment
10 questions
Section 5: The Physiology of Diving

Cellular respiration. Red blood cells and plasma. Haemoglobine. Carbon monoxide poisoning.


The heart, veins and arteries. Baroreceptors and the carotid sinus reflex.


Trachea, bronchi, bronchioles, alveoli and pulmonary capillaries. Gas exchange and dead airspace.


Breathing reflex and hypercapnea. Hyperventilation and shallow-water black-out. The Mammelian Reflex.


Pulmonary and Central Nervous System Oxygen Toxicity.


Different gases, different narcotic effect. Signs and symptoms.


Excessive super saturation and gas seeds/micronuclei. Silent bubbles. Type I decompression sickness: pain only, skin and joints. Type II decompression sickness: dangerous pulmonary and cerebral symptoms.


Decompression sickness risks and efficiency of the circulatory system.


# video


Outer ear, middle ear and inner ear. EustachianTube and equalisation: Valsalva and Frenzel. Ruptured eardrum, and reverse blocks.


# video

The Physiology of Diving
10 questions
Section 6: Decompression Theory

Exponential nitrogen filling of tissues: half times. Fast and slow tissues.


Compartments and theoretical tissues. Different decompression models The nitrogen loading of a compartment in pressure in metres of seawater.


M-values as maximum nitrogen loading of compartments. Different models use different M-values. Computer models use conservative M-values, Bühlmann M-values, Fast compartments and high M-values, slow compartments and low M-values. The controlling compartment


The surface interval. EE washout models.

Decompression Theory
11 questions
Section 7: Summary
Final Quiz
55 questions

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Instructor Biography

Sally Powell, Experienced Scuba Diving Instructor

I am a British diving instructor and I have a lot of experience teaching scuba diving at all levels. For many years I have run divemaster programs and taught instructor development courses at some of the biggest dive centres around the world. I have always enjoyed teaching the theory of diving and want to share my knowledge with you.

Instructor Biography

Marc Luxen, Professional Dive Instructor and psychologist

I am a Dutch dive instructor with a PhD in psychology. I have taught diving for professionals for years in some of the biggest schools in Asia, on all levels. I like teaching, in pools, in lectures halls and in the ocean. I think internet courses are a great way of changing the way we teach and learn.

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