The topic that we are most frequently concerned with is Deco theory: What happens to inert gases in our bodies during diving? How can one ascend to minimize the risk of DCS? What calculation models are there? How are gradient factors used? Is it better to stop deeper or shallower? What is known about individual risk factors?
We discuss all these topics in great detail in our book “Deco Theory – Decompression in Diving”, published in 2025 by Zeisig Verlag.
On these pages, you will find the online version – little text, many tools, a completely different way to learn about the topic. You can log in at the top of the page if you already have access, or purchase the course.

Welcome to our online course on deco theory

Here you will find a complete program on the subject of decompression. We ensure that the fundamentals of all deco models become truly clear and also delve into aspects of technical diving. There is a very practical block on dive planning. And because there is so much more to say on the subject, we look at further research, the topic of Human Factors, and why decompression is such an important issue—namely, decompression sickness (DCS). You will find relatively little text here, but many interactive tools instead.
This allows you to work through the topics so that, by the end, you truly know how to apply all the theory to your diving practice.
The course is divided into individual blocks. You don’t have to work through them one after the other; instead, you can choose what interests you most at the moment.

Deco Theory Book Cover
First aid - Image: Mares

Fundamentals

Bühlmann, half-times, M-values, gradient factors – the fundamentals of deco theory

Graphic M values

Deco Gases and Helium

Why deco gases are so effective, when Trimix becomes the better choice, and a few tips on the best way to dive with them.

Dive Plan with Subsurface

Deco Practice: Dive Planning

Planning specific dives.

Read book

Discussions and Research

Repetitive dives, deep stops, flying after diving, preconditioning – discussion points for further research.

Graphic M values

Human Factors and Stigma

Why isn’t DCS viewed like any normal sports injury? Why we should talk more about diving incidents, and the best way to do so

Emergency Oxygen DAN

Everything About DCS

Symptoms, first aid, frequency – with risk scenarios & checklists to take with you.

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