Technical Diving, An Introduction

Technical Diving - An Introduction by Mark Powell

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Technical Diving - An Introduction by Mark Powell provides recreational divers wanting to know more with a working understanding of technical diving and what is required in terms of equipment, attitude, knowledge and skills to make the transition.


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How can we help?

If you need to contact us for any issue or assistance, you can do so online by filling out the online Contact Form, emailing us at or calling us on +44(0)1305 824 555. If it's about a purchase you've made for us please also include your order number.

Our brick-and-mortar store Underwater Explorers based on Portland, Dorset is staffed 7 days a week, including weekends and bank holidays. As it's an active store visited by divers from around the country and world regularly, if we can't make it to the phone for any reason please leave a message and we'll get back to you asap.

Any queries are usually answered the very same day and at most within 24 hours.


Why Portland?

We’re located on the Isle of Portland (in Dorset) because Portland has been one of the most popular scuba diving locations in the United Kingdom even before we set up operations here back in the year 2000.

On one side, we’re minutes away from the sheltered waters of Portland Marina and Harbour, while on the other, it’s just a brief walk to reach our famous scuba diving destination Chesil Cove and start of the 16-mile-long Chesil Beach.  

Portland’s location makes it ideal for scuba diving, freediving, snorkelling and other surface water sports activities. 

Check out how many wrecks we have around here by clicking on Scimitar Diving's Wreck & Dive Sites chart!

Alongside dive clubs, many instructors and dive schools travel here to train and offer scuba diving certification ranging from open water diver to mixed-gas tech diving or rebreather diving levels.

Whether you’re doing a boat dive from Portland Marina or Castletown or a shore dive at Chesil Cove, Portland is well known for offering many possibilities: Reef diving to wreck diving and night diving, underwater photography or underwater videography. Anything other than cave diving is possible here.

Likely being the best-stocked diving shop in the UK, at Underwater Explorers we offer in-store scuba diving equipment advice and sales, as well as gas fills, to locals and visitors (read About Us).

But... If you’re googling “scuba diving shop near me” like some, look no further, there's DirDirect online.

Here at DirDirect, we list our cutting-edge equipment for worldwide delivery and we’ve got you covered whatever your level of diving: We’re your local dive store wherever you are in the world.

All that with over 20 years of experience especially in technical diving, from training to equipment, advice and sales.


Underwater Explorers, Unit 1, Maritime Business Centre
Mereside, Portland, Dorset, DT5 1FD


Technical Diving - An Introduction by Mark Powell provides recreational divers wanting to know more with a working understanding of technical diving and what is required in terms of equipment, attitude, knowledge and skills to make the transition.

The aspiring technical diver will be able to make clear decisions regarding their training and the type of diving they wish to pursue. Existing technical divers will find guidance on techniques, training and the multiple options to expand their skills.

The modern technical diver is faced with a myriad of options with regard to training, equipment, procedures and choices.

For new and even experienced technical divers, deciding which options are best for your diving style can take time and effort.

Mark Powell analyses the options available in a clear, unbiased manner. Each topic is discussed in plain English, and the pros and cons of each side of the topic are discussed and presented. Readers will benefit from Mark’s considerable experience as a technical diver as he provides counsel and advice where necessary to guide.

Today, nitrox is nearly ubiquitous among sport divers and helium mixes are the gas of choice for deep diving—deep air diving is no longer considered acceptable. In fact, several training agencies are even beginning to introduce helium mixes for recreational divers conducting exposures in the 30-40m range to improve diving safety.

Recreational diving equipment has also felt the influence of tech. Backplate and wings that enable divers to maintain their trim & buoyancy better are gradually replacing old-style vest BCDs; recreational divers are beginning to opt for a long hose versus an “octopus” for their secondary regulator to aid gas sharing, and nitrox and mixed gas dive computers are commonplace.

What’s more, “tekkies” now represent the largest user group of rebreathers on the planet, surpassing the combined militaries of the world.

It’s no wonder then that there is considerable interest in technical diving among avid recreational divers, making technical diving educator and shipwreck diver Mark Powell’s latest book so timely and important.

Mark Powell, the author of “Deco for Divers,” provides interested divers with a thoughtful overview of the field, including its historical and philosophical underpinnings, equipment configurations, fundamentals of mixed gas technology, the required attitude and skills, practical considerations and the issues that tekkies care about most, especially staying alive.

Mark Powell begins by examining the origins of tech diving, what it is and is not. Back in the early 1990s, the difference between technical and recreational diving was stark. That’s not the case anymore and Powell does a great job of describing the continuum of the activity that is now sport diving: from the holiday snorkeler lazily finning across a reef to a dedicated team of tekkies making a 150-meter jump on a newly discovered shipwreck.

Along the way he explores why tech diving has become so popular, what it takes to become a tech diver, and offers practical advice on how to make the transition.

From the beginning, technical diving has been about improving diving safety and performance, enabling divers to conduct exposures beyond the limitations of early recreational diving. Accordingly, Powell discusses the increased risks of technical diving and the mindset and requisite skills, such as value shutdowns and bail-out strategies that tech divers employ to mitigate these risks, including expecting the unexpected and what to do when things go wrong.

Powell offers a detailed discussion of the diving systems or platforms used by technical divers, specifically back-mounted twinsets or doubles, sidemount systems, and rebreathers, along with the advantages and disadvantages of each.

He delves into the fundamentals of mixed gas technology, which is at the heart of tech diving, and practical considerations such as sizing cylinders and stage bottles. He also discusses decompression diving, including the use of mixed gas dive computers, trending topics such as the efficacy of “deep stops,” and what to do for missed decompression.

An important consideration in tech diving is whether to dive as a team or solo diver. Powell provides an in-depth examination of the various approaches to team diving, including diving as a team of one, and their pros and cons.

He also discusses the special considerations involved in diving in cave and shipwreck environments and in expedition diving.

Format: Softback
Pages: 248
Edition: Edition 1
Publication Date: December 2018


Part 1 - Introduction
1. Introduction to Technical Diving

Part 2 - Approach
2. What is Technical Diving?
3. Why has it become so popular?
4. Moving into Technical Diving
5. What makes a Technical Diver?
6. Fitness for Technical Diving
7. Technical Diving and the Internet
8. Comfort Zone
9. Expect the Unexpected
10. What went wrong?
11. Complacency

Part 3 - Equipment
12. Equipment Configuration
13. Twinset configuration questions
14. Side mount
15. Backplate, Wing and Harness
16. Hogarthian Equipment Configuration
17. Reely important equipment
18. Staying Comfortable
19. How many cylinders do you need?
20. Dive Computers
21. What’s in your Argon bottle?

Part 4 - Skills
22. Buoyancy Control
23. Trim
24. Finning Techniques
25. Reaching Your Valves
26. Shutdown Drills
27. Individual or Team Diving
28. Team Sizing
29. Problem Solving
30. Technical Skills

Part 5 - Rebreathers
31. Rebreathers
32. Rebreather configurations

Part 6 - Aspects
33. Extending your diving – Longer rather than deeper
34. Decompression Diving
35. Nitrogen Narcosis
36. Trimix
37. Oxygen Toxicity
38. Dive Planning
39. Wreck Penetration
40. Cave Diving
41. Expeditions
42. Missed Decompression

SKU: 978-1905492312