The Short Answer
If you’re curious about rebreathers — how they work, how they’re built, or how to get the most out of one — this site is for you.
It doesn’t matter whether you’re a seasoned technical diver with thousands of hours on closed circuit, or someone who’s just heard the word “rebreather” for the first time and fallen down a rabbit hole. We’ve built this site to be useful at every level, from the fundamentals right through to advanced engineering. Pull up a chair, have a look around, and take what you need.
You Might Be...
You’ve seen rebreather divers gliding silently past you on the reef and wondered what all the fuss is about. You’re not sure you want to build one — you’re not even sure you want to dive one yet — but you’d like to understand what they are, how they work, and what the options look like. No commitment, just curiosity.
You already dive rebreathers — maybe you own a commercial unit, maybe you’re training on one — but you want to understand the engineering behind the machine, not just the procedures for using it. Why does your scrubber last as long as it does? What’s actually happening inside that orifice? How do the sensors decide what to inject? You want the “why,” not just the “how.”
You want to design and build your own rebreather. Maybe you’re an engineer who enjoys a challenge. Maybe you’re a tinkerer who’s happiest in the workshop with a lathe and a cup of tea. Maybe you just looked at the price of commercial units and thought “I could do that.” Whatever the reason, you want practical guidance, proven designs, CAD files, and the confidence to do it properly.
You already own a commercial rebreather, and it does the job. But you’d like to understand it well enough to maintain it with confidence, troubleshoot problems yourself, or make modifications that suit your diving better. You’re not looking to throw out the manual — you want to go beyond it.
You’re not here for the prose — you want the numbers. Scrubber capacity data, orifice sizing calculations, absorbent performance comparisons, gas physiology reference tables. You know what you’re looking for and you just need a reliable, well-organised source.
A Note on Diving Experience
We’ve done our best to write everything on this site in clear, accessible language. Technical terms are explained the first time they appear, analogies are used liberally, and we’ve avoided jargon wherever we can. You shouldn’t need an engineering degree to follow along.
That said, rebreather diving doesn’t exist in a vacuum — it sits on top of a foundation of open-circuit diving knowledge. Concepts like partial pressure, gas narcosis, oxygen toxicity, decompression, and Boyle’s Law come up frequently throughout the site. If you’re a certified diver, these will be familiar ground. If you’re not, some of the material may feel like walking into a conversation that’s already started.
That doesn’t mean you’re not welcome. Far from it. But we want to be upfront: readers without diving experience or a basic understanding of diving physics and physiology may find some content challenging. We’d rather be honest about that than leave you feeling lost halfway through a guide.
If you’re new to diving entirely, consider starting with a basic open-water diving course before diving into rebreather theory. It’ll give you the foundational knowledge that makes everything on this site click into place — and it’s a fantastic experience in its own right.
Who This Site Isn’t For
We’d love to say this site is for absolutely everyone, but honesty matters more than inclusivity theatre. There are a few expectations that come with using rebreathology.com, and it’s worth being clear about them.
This is not a shortcut to skip training
Nothing on this site replaces formal rebreather diving training with a qualified instructor. We provide knowledge, not certification. If you’re hoping to read a few guides and then jump in the water with a home-built unit and no training, this site will actively discourage you from doing that — because it’s dangerous, and we’d rather lose a reader than contribute to an incident.
This is not a commercial parts catalogue
We don’t sell anything. The CAD library, the guides, the tools — they’re all free and open source. If you’re looking for a shop, you won’t find one here. What you will find is the knowledge to make informed decisions about what to buy and where.
This is not a certification programme
Reading this site doesn’t certify you to build, inspect, or dive a rebreather. There is no exam at the end, no certificate to download, and no badge to display. What you gain is understanding — and understanding is what keeps you safe. But it’s not a substitute for recognised training and supervised experience.
This is not a place to cut corners
If you’re looking for the cheapest possible way to get underwater without regard for safety, engineering standards, or proper testing — you’re in the wrong place. We’re all for budget-conscious building, and we’ll show you where you can save money without compromising safety. But we’ll never help you compromise safety to save money. There’s a difference, and it matters.
A rebreather is life-support equipment. Building one is a rewarding project, but diving one is a serious undertaking. We want every reader to succeed — and that starts with being honest about what success requires.
Where to Start
However you’ve arrived here, there’s a sensible starting point for you:
Brand new to rebreathers? Start with Part I. It’ll introduce you to the different types of rebreather, explain the key concepts, and help you decide whether building one is right for you.
Understand the basics, want to go deeper? Part II covers every major component in detail — scrubbers, breathing loops, gas addition systems, sensors, and more. It’s the reference section you’ll keep coming back to.
Ready to build? Part III is where the workshop starts. Begin with the Foundation section and work through at your own pace. The build guides are modular, so you can pick the type of rebreather you want and follow the path.
Just here for the data? The Appendices and interactive tools are there whenever you need them — scrubber databases, gas calculators, orifice sizing tools, and more.
Whatever route you take, remember: there’s no rush. Take your time, understand what you’re reading, and enjoy the journey. The water will still be there when you’re ready.