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Deep stops done before dcs
Deep stops featured in dive computers

- Ocean Image Photography

If you are new to diving, or even a regular diver who wants to buy a new dive computer, you will notice more and more of them are now implementing the option of using deep stops.

Since most non-technical diver training does not really talk about deep stops, here is the low down on what they are, and where they come from.

A Slice of History

The term ‘deep stops’ and the idea behind them was invented by Dr. Richard Pyle in the late 90’s. Dr.Pyle, who in his own words is an ichthyologist or ‘fish nerd’, noticed that when he was doing his deep dives he felt really fatigued after some dives, whilst after some others he felt excellent.

Being the enterprising scientist that he is, he started collecting data on every aspect of his dive to find out why this phenomenon occurred. After some research, he discovered that he normally felt less fatigued after dives on which he collected fish samples, whilst on dives he didn’t, he felt much more fatigued.

Refusing to accept that is was a psychosomatic happy effect of having collected a fish sample, he had his Eureka moment.

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Deep stops discovered by Dr. Pyle

A photo of young Dr. Pyle scuba diving taken decades ago - Credit: TED


Dr. Pyle realized that when he collected fish samples, he would stop several times on his ascent. These stops were much deeper than normal, and for about a minute each stop. He did this to syringe gas out of the fishes’ swim bladder, so it didn’t explode on ascent and ruin the sample.

He realized that these little deep stops were also allowing his body to off gas his fast tissues, preventing the formation of silent bubbles which are the main culprits of post-dive fatigue.

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Diving with Fast Tissues and Silent Bubbles?

Basically, the human body does not supply blood equally to all its parts - so your brain, heart, and muscle tissue get much more blood than fat and bone. Since when we dive, our on-gassing and off-gassing is controlled by this rate of blood supply, which moves the inert gas around, some tissues can move inert gas much quicker than other ones, and so we have fast tissues and slow tissues.

Silent bubbles basically happen on every dive, especially the deeper ones. They are bubbles that form in our body that are so small that they are incapable of causing blockages in the circulation and cause DCS. However, when you do have a lot of them, they cause a lot of post-dive fatigue. So it’s best to use ascent strategies to try and minimize the number of these bubbles in our body.

Here's Slowing Down As If Your Life Depended On It.

Deep stops with good ascent strategies

Divers with good ascent strategy minimize slient bubbles - Credit: C.K.Ma

Where we are today with Deep Stops

Today, there are several different methods to calculate deep stops. Without going into great depth about each one, most recreational dive computers use a methodology that is very close to Dr. Pyle’s method of calculation.

However, most technical diving computers use a method called gradient factors, which actually determines the stop depth using the tissue loading data during the dive.

While some people swear by deep stops and some people don’t see the point of doing them, they are still a good thing to implement in your recreational diving plans, since they give you an easy way to control and slow ascents from dives.

Also, deep stops won’t hurt you, and they can add a bigger safety margin to your dives. Whatever you choose to do, have fun and dive safe.