Let’s Go Deep!
Over the past couple of days 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. 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.
Do you want to get “narked”..??
There are skills students must complete on each dive. These include monitoring the affects of nitrogen narcosis. Nitrogen narcosis is a reversible alteration of consciousness that occurs while diving at depth. It’s not dangerous – as long as you understand the signs and symptoms, and have experienced these, under direct Instructor supervision.
Nitrogen Narcosis occurs because of an anaesthetic effect that affects gases under pressure. It essentially gives you the sense of euphoria, possibly some disorientation but mainly just a happy feeling and makes you laugh. People have said it gives you same sensation as being a little drunk. This normally affects people when they go deeper than 30metres.
Day 1 and the first dive was PADI Deep Diver training dive # 2. We looked at the effects of pressure at depth on flexible items. I decided to bring two empty plastic water bottles and a bag of crisps. My students where also required to complete a small navigation skill at depth. I reminded my students what they had learnt on the Deep Adventure Dive they completed as part of the PADI Advanced course.
We discussed the importance of monitoring air more closely. I also reminded them of how colour dissipates at depth. First red dissipates then orange, yellow and green, something covered on the first training dive.
The Best Dive Sites
Opening up a world of opportunity….
With the Academics done, bags packed, lunch eaten, and the boat ready we headed to Southwest Pinnacle, in my opinion, 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.
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 these objects.
On the surface I filled one of the water bottles up 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. The same happened with the bag of crisps which looked less than half its original size and much less colourful.
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. Then with one of the guys approaching the 50bar, low on air limit, we moved up and completed our safety stop before heading to the surface.
Back on the boat we compared the objects again. We discussed why they had returned to original size at the surface where the ambient pressure was 1atm.
40 metres – The Ultimate Challenge!
The second day we took the morning boat to Chumphon Pinnacle, another of the ‘Big 3’ dive sites. It is known for its almost limitless visibility on a good day and the vast array of fish life. It is also one of the best sites to spot Whalesharks in Thailand. Chumphon Pinnacle is situated around 10 km’s from Koh Tao. It takes around 30 – 40 minutes to travel to and is the deepest recreational dive site local to the island – Sail Rock is a couple of hours away and requires a full day trip.
During the journey to the site I conducted the first part of my favourite skill in the entire PADI system – the narcosis test! This is a simple game or quiz I ask my students to complete on the surface, before the dive and again during the dive at 40 meters. Every PADI Instructor has a method to test nitrogen narcosis….
I have series of numbers, jotted down on my slate form 1-12. I put different numbers inside shapes; a triangle, a square or a circle. The three shapes correspond to parts of the head; triangle to nose, square to head, circle to ear. Then they have to count, either forwards (1-12) or backwards (12-1) whilst touching the corresponding part of their body to the shape that the number is inside.
On the surface Antoine scored 26 seconds whilst Jerome was slightly slower taking 30 seconds. We planned a shorter dive as we were going to 40 metres. At that depth our No Decompression Limit (NDL), according to the PADI Recreational Dive Planner (RDP), was a maximum of 8 minutes. We were diving on computers; the Mares Puck – so we planned a multi level dive which allowed some additional time at shallower depths. We descended straight down to our maximum depth of 40 metres and knelt in the sand.
Firstly I gave Antoine the test. I could see him smirking and laughing a little whilst doing it, completing the task in 38 seconds, 12 seconds slower than he had done on the surface! At this point I turn to Jerome whois laughing and pointing at a fish that is swimming between the three of us. Jerome begins the test. All I can see are lots of bubbles coming from his Regulator from all his laughter.
After 30 seconds he throw’s my white slate, containing the test, on the ground and decides just to enjoy the feeling of narcosis. Sitting without a care in the world I hand him the slate back and 4 minutes 30 seconds later he finishes the test!
We have 3 minutes of no stop time remaining. We begin to ascend immediately to a shallower depth to relieve the signs and symptoms of narcosis and give us a little more no stop time. At the end of the dive we ascend to 5 metres and complete the 8 minute simulated decompression stop, the final performance requirement of Deep Diver training 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, if only for the pure comedy factor!
The Final Dive
Deep Diver training dive 4 is essentially a fun dive. The dive site is Green Rock, located on the North West side of Koh Nang Yuan. We plan a maximum depth of 25 metres. Checking our no stop time on our dive computers as well as monitoring our air closely, we swim around the dive site.
Under one side of the pinnacle we spot a sleeping Jenkins Whip Ray with a wingspan of around 2 metres, one of the larger ones I have seen. With the trigger pit on the north side of Green Rock it is incredibly difficult not to see a Trigger fish here. With 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. As well as learning how to plan and execute Deep dives safely we also learnt what to do if you accidently exceed your NDL. 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!
And of course the course shows divers the benefits of diving deeper dive sites, highlighting the opportunities open 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)