Dive training is based on a series of guidelines and rules of thumb, but no two divers are the same. Everyone is impacted by nitrogen narcosis, DCS and other variables differently.
Have you been diving at a reef edge or a vertical wall where you see life at greater depths? Do you want to go deeper, but your training and experience limits you?
Here are some facts that you need to know about deep diving.
What is Deep Diving?
Deep Diving is any dive deeper than 20 meters (60 feet). However there are different kinds of diving which gives deep diving its own specific definition. In Recreational dive, the maximum depth limit is 40 meters (130 feet).
In technical diving, a dive deeper than 60 meters (200 feet) is described as a deep dive.
However, as defined by most recreational dive agencies, a deep dive allows you to descend to 18 meters and beyond.
Risks in Deep Diving
Deep diving is relatively safe as long as you follow all the rules and procedures. However, it is important that you know the inherent risk of diving at greater depths.
Decompression Sickness (also called the bends)
When you dive, you breathe in air which is composed of oxygen, nitrogen and other gases. Your body uses the oxygen but nitrogen is eventually released over time since our body does not need it.
So, when pressure suddenly drops, like in the case of a rapid ascent, nitrogen gas inside your body expands and develops into bubbles. These bubbles are usually trapped in the joints causing severe pain. A diver with decompression sickness is treated using hyperbaric oxygen therapy inside a recompression chamber.
Nitrogen Narcosis
You will experience a narcotic effect when you accumulate too much nitrogen. The first symptoms are tingling of the fingers, dizziness and disorientation. It also affects your sight by experiencing a tunnel vision which makes reading gauges and instruments difficult. The deeper you go, the greater the effect of nitrogen narcosis is.
Rapid Air Consumption
The air you breath will become denser as you go deeper due to increasing pressure. Meaning, you consume more air while deep diving as compared to diving at shallower depths. So it is highly recommended that you constantly monitor your pressure gauge.
You can also bring an additional small cylinder or a pony bottle, some stage a decompression tank at the safety stop line.
Rules, Recommendations and Tips for a Safe Deep Dive
Do’s
- Plan your dive. Establish your maximum depth and bottom time.
- Always perform the Pre-Dive Safety Check before diving.
- Regularly monitor your depth and pressure gauge. Make sure that you have plenty of air in your tank for your ascent.
Don’ts
- Do not plan your dive so that it exceeds the No Decompression Limits of the dive table.
- Never dive alone and always have an experienced buddy with you.
- Never go beyond your planned depth nor exceed your bottom time.
How to Get Started
Your first deep dive should be under the supervision of a dive instructor. You can do this during your Advanced Open Water Diver course. You will be trained to dive to a depth of 30 meters (100 feet). You may also have the option to enroll in a Deep Diver Specialty course wherein you will be trained to dive as deep as 40 meters (140 feet).
After your certification, you may plan to go deep diving with an experienced dive buddy. Some deep diving sites may take you to shipwrecks or may require you to use an enriched air to extend your dive time. So you may also consider enrolling in other specialty courses like wreck diving, peak performance buoyancy and enriched air diver.
Dive as it’s any other dive
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- Get in the water and set your dive watch and establish orientation or direction using your compass.
- Once ready, signal your buddy to start descending and slowly deflate your BCD.
- You should descend closely together until you reach your planned depth. Watch your buddy for signs of Nitrogen Narcosis.
- While descending, you may feel a sudden change of temperature called the thermocline. Just continue with your dive as this occurs naturally.
- Never go beyond your planned depth nor exceed your bottom time.
- Regularly monitor your depth and pressure gauge. Make sure that you have plenty of air in your tank for your ascent.
- Before you start ascending, signal your buddy and you should always ascend together.
- Make sure that you deflate your BCD when ascending to prevent rapid ascent.
- Ascend slowly and strictly follow the normal ascent rate no faster than 20 meter (60 feet) per minute.
- Make sure to do a safety stop at 5 meters (15 feet) for 3 minutes. Deploy your DSMB before your last ascent.
Some of the World’s Famous Sites for Deep Diving
Lighthouse Reef Blue Hole (Belize, Caribbean Sea) – this site was created from an ancient cave system. It almost has a perfect blue circle measuring 300 meters (1,000 feet) in diameter. You can enter an underwater cave where you will be amazed by the amazing stalactite formation. You can also reach a deep coral reef that starts at 33 meters (110 feet) and slopes down to 135 meters (450 feet).
Blue Hole (Dahab, Egypt, Red Sea) – known as one of the world’s most dangerous dive sites due to the number of lives it had claimed.
You start your dive by descending through a vertical hollow space in between coral mounds. You will exit through at 27 meters (90 feet) in clear water where you will find a vertical wall. This wall plunges further down to profound depths.
Blue Corner Wall (Palau, Micronesia) – You will definitely enjoy this vertical drop-off that starts at 10 meters (30 feet) and plunges down to over 330 meter (1,000 feet) deep. You will find large schools of fish, sharks, turtles, giant groupers, barracudas and many more. Blue corner wall is considered as one of the best dive spot in the world.
Deep diving sites are not only confined in saltwater environments. The Eagle’s Nest Sinkhole in Weeki Wachee, Florida is a freshwater pond. Underneath lays a large chamber with crystal clear water. You start your descent by entering a chamber that leads to the “Main Ballroom”. This is a very large and deep cavern that plunges up to 91 meters (300 feet) deep. Eagle’s Nest is considered as the Mount Everest of Diving and one of the world’s complex dive sites.
World’s Deep Diving record
With the purpose of connecting an underwater pipeline, a team of commercial divers reached a depth of 534 meters (1,752 feet). They used a specially-mixed breathing gas for this job. This happened in 1988 off the coast of the Mediterranean Sea.
The deepest scuba dive was recorded at 318.25 meters (1,050 feet). This was performed in 2005 in the Red Sea by a 52 year old Engineer named Nuno Gomes. This dive was declared as the Guinness World Record for Mankind’s Deepest Dive.
The world’s deepest wreck dive was recorded at 205 meters (676 feet) while diving in the Yolanda Wreck in Egypt. This was performed in 2005 by Leigh Cunningham and Mark Andrews.
Why is 130 Feet the Depth Limit for Recreational Scuba Diving?
Dive training is based on a series of guidelines and rules of thumb, but no two divers are the same. Everyone is impacted by nitrogen narcosis, DCS and other variables differently.
So why has every major training agency established 130 feet — 40 meters — as the depth limit for recreational dive? In order to venture further and explore wrecks, caves and other sites beyond 130 feet, these agencies — such as PADI, NAUI and SSI — require “technical” certifications.
This precedent can be traced to the U.S. Navy, which established the rule in the 1950s and still requires special permission from a commanding officer for a diver to exceed this limit.
THE 10-MINUTE SHIFT
“The 130-foot limit is an arbitrary depth originally adopted by the U.S. Navy because it gave Navy divers about 10 minutes of (no-deco) time on compressed air; going any deeper on air made no sense to the Navy because the time available to do useful work was simply too short,” writes Lawrence Martin in Scuba Diving Explained: Questions & Answers on Physiology and Medical Aspects.
Sure, you can go deeper than 130 feet without mandatory decompression stops, but you’re not going to have much time to get anything done.
“(130 feet) is an appropriate limit for single-cylinder no-stop diving with air because of the short no-stop time you have, plus the relatively quick consumption of your gas supply,” says Karl Shreeves, PADI’s technical development executive. “It is also the depth by which almost all divers begin to find gas narcosis noticeable.”
BREATHING DEEP
When considering deep diving in the 1950s, you have to examine the equipment available at that time.
“In the early years of open circuit, the depth limit in the U.S. Navy was set at 130 FSW primarily because of the lack of good breathing performance. To dive deeper than 130 FSW on a double hose was extremely risky,” according to the experts at Dive Lab, a scuba equipment testing facility in Panama City Beach, Florida.
BETTER SAFE THAN SORRY
Another factor to consider is the U.S. Navy’s dive table, which lists a dive to 140 feet as having the same no-deco limits as a dive to 130 feet. Both allow for 10 minutes of no-deco time, so why not set the recreational dive limit to 140 feet?
“With tables, even going 1 foot beyond the increment mandates you move to the next increment. So, if you had a maximum depth of 140 feet and allowed yourself to descend to 141 feet, by the tables you would have to calculate the dive as 150 feet,” says Eric Douglas, a scuba safety writer and former instructor. “If you failed to notice that until you returned to the surface, you could be in a situation where you had omitted obligated decompression and, according to the tables, you couldn’t dive for 12 to 24 hours.”
So a limit of 130 feet allowed a slight margin for error — a welcome factor for divers who’d never heard of a computer.
THE MODERN MAN
Times have changed. Almost every recreational diver now sports a computer and a regulator that breathes smoothly beyond 130 feet. So why does every major training agency require a “technical” certification to venture beyond? Simply put: Better safe than sorry.
“Tec diving, which emerged in the late 1980s, uses high capacity cylinders and/or CCRs (closed-circuit rebreathers), plus helium-mix gases, to go deeper than 130 feet while reasonably managing the associated risks,” says Shreeves. “With such equipment and the associated training, the dive community recognizes that the 130-foot limit doesn’t apply.”
There are plenty of valid reasons to dive deep, but it requires a thorough knowledge of decompression stops, emergency procedures and the effects of nitrogen narcosis.
At face value, the 130-foot limit seemingly decreases training agencies’ liability by encouraging divers to stay shallow. But it’s not necessarily a good thing, according to author and dive pioneer Brett Gilliam.
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