12 Diving Concepts You've Never Learned or Already Forgotten

A Review of Important Dive Theory

A major problem exists with any open water course. Although a scuba instructor teaches his students how to react to common emergency scenarios, he cannot anticipate every potential problem that his students may face underwater. A good instructor introduces student divers to the rules of safe diving, but more importantly, he focuses on the concepts behind those rules. The goal is that scuba diving students graduate with a working knowledge of the physics and physiology of diving, as well as the ability to apply that knowledge to unexpected situations. This page lists concepts that every scuba diver needs to understand to dive safely. Scroll down to see an overview of topics, or click on the link that interests you below.

Image copyright istockphoto.com, Tammy616

As a professional diver, people ask me all the time “Doesn't scuba diving hurt your ears?” Many potential divers have experienced ear pain when diving down in a swimming pool because they did not properly equalize the pressure in their ears. These people are worried that they will experience the same sensation when scuba diving. Relax, most people can equalize their ears easily with the techniques outlined in this article. Read more More »

female scuba diver
Image copyright istockphoto.com, Tammy616

How does pressure change underwater and how do pressure changes effect aspects of scuba diving such as equalization,buoyancy, bottom time, and the risk of decompression sickness? Review the fundamentals of pressure and scuba diving, and discover a concept no one told me during my open water course: that pressure changes more rapidly the closer a diver is to the surface. Read more More »

Female diver on a wreck.
Mastering the command chain allows control in the most difficult diving environments. © Getty Images

 This article be technical diving instructor Vincent Rouquette-Cathala will change you diving. Read it! More »

Underwater photo of a female scuba diver in warm tropical water
Image copyright istockphoto.com, Mark_Doh

Understanding buoyancy is key to safe and easy scuba diving. While the concept of buoyancy may be confusing at first, it becomes clearer when we consider how buoyancy effects scuba divers and what divers need to know to properly control it. Here is a definition of buoyancy, an overview of how it applies to diving, and step-by-step explanation of how to control buoyancy on an average dive. Read more More »

photo of scuba gear.
Scuba diving gear for open water diving. © istockphoto.com

Whether you are a new open water diver or an advanced technical diver, these quick guidelines will help you to evaluate your equipment configuration for safer, more comfortable diving.   More »

Buoyancy.jpg

"Trim" refers to your body position in the water, and it can make or break your dive. It's so important that I wrote a whole series of articles about it:

Why Is Trim Important?

5 Ways to Position Your Body for Proper Scuba Trim

• 7 Equipment Adjustments for Better Trim

. More »

Senior Diver
Senior Diver. Getty Images

It's easy to just drop down on a shallow reef and putter around without much planning. But, no matter how deep your dive is, you should calculate your no-decompression limit for every dive, and have a few contingency plans including exceeding your planned depth or time. If you don't do this, you run the risk of getting bent. More »

scuba diving friends
Three Happy Scuba Divers on the Surface. © istockphoto.com

 It's unfortunately common for divers to forego predive checks after certification. That's silly! The simple predive check takes under a minute to complete and will prevent most equipment related problems.  More »

natalie l gibb

Having clear communication underwater makes diving so much easier. If you don't remember the most common scuba hand signals, this illustrated guide will help. More »

Passive Communication for Scuba Diving

dive buddies
A scuba diving buddy team. © istockphoto.com

The single most helpful lesson I can give divers for good communication and smooth diving is to use their team position and lights (if they have them) for communication. If you have never heard about this concept, now's the time! 

© istockphoto.com, Tammy616
A diver's air consumption rate is a useful in many ways - in dive planning, in evaluation of stress, and in identifying faulty dive gear. Learn how to calculate your air consumption rate and how to use it to plan dives. More »
Photo of sponges
Image copyright istockphoto.com, popovaphoto

A diver's body absorbs nitrogen during every dive. Understanding nitrogen absorption is important for recreational scuba divers because many of the safe diving practices are based on this concept, such as maximum allowable dive times, flying after diving rules, and ascent rate recommendations. The sponge analogy will help you to understand the fundamentals of nitrogen absorption. Read more More »