Let’s Go Deep!
Recently I’ve had the opportunity to conduct my favourite PADI specialty; the PADI Deep Diver course. In my eyes this course is crucial for any recreational scuba diver who dives regularly. For myself there’s something exciting and mysterious about exploring deeper dive sites while scuba diving. Sometime it’s a wreck that attracts you below 18 meters, or an opportunity to see some sharks. Whatever it is, to dive with confidence at depth down to over 30+ meters, the PADI Deep Diver Specialty Course help you prepare for it. We teach students how to plan and execute Deep dives. We also look at effects additional pressure at depth has, on the diver, their air supply, colours and flexible objects.
The course itself consists of four training dives and is scheduled over two days on Koh Tao. A student must hold a minimum PADI Adventure Diver certification to enrol. In reality, here on Koh Tao, almost all our Deep Diver students already hold the PADI Advanced Open Water cert as was the case today with my students Antoine and Jerome.
As Antoine and Jerome had already completed the PADI Deep Adventure Dive as part of their Advanced Course, this is credited towards the Deep Diver certification, which means they only have to complete training dives 2, 3 & 4. Although it was necessary to take a review of the course theory. With deep diving (and with any dive for that matter) the planning is important, reviewing procedures like maintaining good buoyancy, the buddy system and knowledge on Nitrogen Narcosis.
Do you want to get “narked”..??
Deeper diving is incredible, but to be competent to be able to dive to 40 meters you will need to understand the physiological and psychological effects of Deeper Diving, The skills that you learn on the PADI Deep Diver course includes how to monitor and look out for the effects of nitrogen narcosis. Nitrogen narcosis is a reversible alteration of consciousness that occurs while diving at depth. This is all very manageable and as long as you understand the signs and symptoms and they can be easily remedied by ascending to a shallower depth. Narcosis itself is not dangerous, but being too confident and having impaired judgement can cause an issue during the dive.
Nitrogen Narcosis is typically experienced by divers who dive to depths of 30m plus. It is described as a feeling of happiness and overly positive sense of wellbeing. Every person is different and Nitrogen narcosis varies between divers and can make it difficult to predict.
During the first day, we looked at the effects of pressure at depth. A good way to demonstrate this is to bring two empty water bottles, which will compress under the pressure change caused by the water depth. My students had not long previously completed PADI Advanced course and so I reminded them of what they had learned during that course, as they were required to complete a small navigation skill at depth.
Obviously the deeper you dive the more air consumption you will use and so we discussed the importance of monitoring air more closely during the dive. Additionally, I also reminded them of how colour dissipates at depth with water absorbing different wavelengths of light to different degrees. The longest wavelengths, with the lowest energy, are absorbed first. Red is the first to be absorbed, followed by orange & yellow.
The Best Dive Sites
Opening up a world of opportunity….
Planning for deep diving is not complex, but it does require a bit of thought and during our preparation and academics we prepared to carefully evaluate how the dive will play out. So with our bags packed, lunch eaten, and the boat ready we headed to Southwest Pinnacle, which in my opinion is one of the three best dive sites in the Gulf of Thailand. The other two sites in this category would be Chumphon Pinnacle and Sail Rock.
On the boat ride to Southwest Pinnacle, I told Antoine and Jerome to look at the items I had brought to get a visual comparison, such as the size of their finger so we could measure the change at depth. The reason for this when light travels from one medium into another, it bends slightly. This occurs because light usually has a slightly different speed underwater.
During the dive visibility under the water was fantastic and as we descended down we could see the whole pinnacle, its vibrant colours swarming with marine life. We spotted a Cobia swimming beneath us, giant schools of scat swimming around the pinnacle. We descend down to 30 metres to see what effect 4 atmospheres of pressure (atm) would have on the bottles I had brought with us.
To demonstrate the effects of compression at depth I used 2 water bottles. Before the dive I filled one bottle with water and left the other empty. At 30m I showed my students the water bottles. They were amazed to see the one with air in had compressed to almost a quarter of its original size whilst the other one filled with water remained unaffected.
I took out my torch and brought their attention to the colour dissipation they had learned about during their PADI Advanced course.
We sat at thirty metres looking at these objects whilst being cocooned by an enormous school of Chevron Barracuda circling around us. At one point all we could see was a silver wall of barracuda, nothing else. Then they dispersed, quickly, probably to hunt their afternoon meal. My students completed the navigation skill which was straight forward, navigating a reciprocal heading at depth.
Back on the boat we compared the objects again. We discussed why they had returned to their original size at the surface where the ambient pressure was 1atm.
40 metres – The Ultimate Challenge!
The second day it was time to go to greater depth and so the dive site Chumphon Pinnacle was selected. This is a great diving location, known for its almost limitless visibility on a good day, with a vast array of marine life. This dive site is also one of the best places to spot Whalesharks and is situated around 10 km’s to the north west of Koh Tao. The travel time to the site takes around 30 – 40 minutes and so gives you plenty of time to prepare and enjoy the beautiful Thai morning weather. Chumphon Pinnacle is the deepest recreational dive site local to the island, the other is Sail Rock, which is couple of hours away and requires a full day trip.
While we were journeying to the site, we prepared for the upcoming dive. On the surface we discussed and demonstrated one of my favourite skills in the PADI system – the narcosis test! This skill is a simple game or quiz. The students complete this on the surface and at depth to show the effects of Nitrogen Narcosis. There are a number of ways to test this and every PADI Instructor has their own method to show the effects of nitrogen narcosis.
The test in which I use to demonstrate Nitrogen Narcosis during the dive is to hold up a number of fingers to your buddy, let’s say two. Your buddy should respond with the same number plus one, so three. If they reply with any number other than three, you should ascend to a shallower depth.
While you can’t build up a tolerance to Narcosis, with experience and training you will learn to recognise and cope with its effects.
With deeper dives your no decompression limits are shorter and must be monitored. We observed that we had 3 minutes of no stop time remaining so we began to ascend immediately to a shallower depth to give us a little more no stop time. At the end of the dive we ascended to 5 metres and completed the 8 minute simulated decompression stop, the final performance requirement of Deep Diver training on dive 3. On this stop the students breathe off a drop tank at five metres.
This skill is designed to show students what to do in the event they need extra air for an emergency decompression stop after a Deep dive. Obviously we were only simulating an emergency decompression stop and allowing the students to practice.
On the boat journey to our final dive, Jerome commented he had experienced nothing like narcosis before. He described his experience as the most enjoyable dive he had ever done.
The Final Dive
Deep Diver training dive 4 is essentially a fun dive. The dive site was Green Rock, located on the North West side of Koh Nang Yuan. Checking our no stop time on our dive computers as well as monitoring our air closely, we dived under one side of the pinnacle. Here we were lucky enough to spot a sleeping Jenkins Whip Ray with a wingspan of around 2 metres, one of the larger ones I had seen. With having local knowledge of the dive site I knew that there was a trigger pit on the north side of Green Rock and there is a good chance to spot Triggerfish here, their lovely colourings and propulsion technique they are always great to watch. We finished our dives and headed back to Crystal.
We had some of the most enjoyable dives during the past two days. Learning how to plan and execute Deep dives safely, we also trained on what to do if you accidentally exceed your No Decompression Limits. The PADI Deep Diver Specialty also covers Decompression Illness and Nitrogen Narcosis, expanding on the knowledge you gained during the PADI Open Water and Advanced courses. And of course how to avoid such things whilst diving!
A great benefit of this course is that it opens up opportunities to divers certified to dive deeper and the huge number of dive sites that are now accessible to you!
Let’s Go Deep!
For more information on this PADI Speciality, visit our PADI Deep Diver Specialty course page.
Author: Luke Smith (PADI MSDT #333122)