Freediving on Koh Tao

Freediving on Koh Tao

Whilst wandering around Sairee Beach to find a good dive shop, I stumbled upon two Freediving schools. I’ve been interested in Freediving for a while, but always assumed it was out of reach, and that you had to be some kind of superhuman to be able to do it. Stumbling across the schools here in Koh Tao got me interested in trying it out for myself.

Freediving is diving underwater without scuba gear: relying on your ability to hold your breath until you resurface. The world record for breath holding is 11 and a half minutes, whilst the deepest freedive is over 200m. Unlike Scuba, surfacing from such depths will not cause the bends (decompression sickness) because no air is breathed underwater at pressure.

As a kid, I used to love swimming underwater in the pool and seeing how far I could go on a single breath, so I wasn’t horrified by the idea. In fact, I was excited to try it. Duncan had decided to go for his Advanced Open Water certification, which would take two days, and I figured that since I wasn’t going to be diving with him, it would be a good use of time to do a 2-day training course.

I picked a school called Blue Immersion on Sairee Beach. I chose it over its competitor because it offered certification and more training time, with a strong focus on theory and breathing exercises.

I turned up early one morning after having a small breakfast (recommended – it’s hard to breathe properly if you’re feeling bloated). Pretty much immediately, we were asked to lie on the deck overlooking the sea and told to breathe deeply with our diaphragms. Breathing in this way ensures the lungs are fully used. We also learned about slowing the breathing whilst deeply breathing to avoid hyperventilation and to calm ourselves. Being calm when fighting the urge to breathe underwater is life or death important.

We were asked to hold our breath for as long as possible and feel how the body reacted with its “Urge to Breathe” response. We were asked to hold until we had felt the diaphragm spasm three times, then to practice “recovery breathing” to oxygenate the blood quickly. With practice, it is possible for relative newcomers to learn to hold their breath for as long as five minutes.

We were also told about the physiological changes the body undergoes to protect itself during a dive. Called the Mammalian Diving Reflex, it occurs strongly in diving mammals such as seals and dolphins, but weakly in humans. Still it’s enough to help us go deeper and for longer. Its effects are:

  • Bradycardia – the heart slows down
  • Vasoconstriction – blood vessels shrink and blood moves from the peripheries to benefit the heart, lungs and brain.
  • Splenic Contraction – The spleen releases more red blood cells into the blood stream to shift oxygen around the body more effectively. This effect also explains the good energy freedivers feel long after freediving: those red blood cells make you feel pretty energetic!
  • Blood Shift – Blood plasma fills up blood vessels in the lung to equalise against the pressure from the water outside. At 10m your lungs halve in volume due to water pressure. At 20m your lungs halve again to one-quarter the volume. At 30m your lungs are one-eighth the volume and would be permanently damaged if not for this reaction.
  • Diuresis – Once you return to the surface, the body has to put the excess fluids it’s just been shifting around somewhere, so they go to the bladder. Then you need to pee. A lot.

Due to the above factors and some others, most blackouts in freediving occur in the top 20m depth, shallow enough to get rescued and revived easily. Needless to say, if you blackout, you should stop diving for the day.

Freediving Boat - Koh Tao, Thailand

After this introduction, we waded into the sea to hop onto a boat, which sailed us out to a suitable spot for the dives that were planned. The beginner’s course needed depths of only 20m, but there were some higher-level classes on the boat as well, so the captain sailed us out to a spot that was 45m deep.

Breathing Up in preparation for a Freedive

The instructors swam out with some buoys on a line and the various classes were assigned, with no more than three to a buoy. My instructor, Steve, lowered a heavy lead weight down into the blue depths. It worked a bit like a plumb line, and this line would be what we worked with as we practiced our descents. I looked down into the water as he lowered it, and lost sight of the weights at the end of the line. It sure looked very far from up on the surface.

In turn, we were asked to prepare for our freedive by doing a “Breathe Up” – breathing in for 5 seconds, followed by a 10 second exhale and repeating this about six times. It is important not to hyperventilate (defined as breathing in and out at the same rate) as this can build up CO2 in the blood and lead to blackouts. Once the Breathe Up was done, it was time to take one final big gulp of air and then go head first down the line, equalising (popping your ears) frequently as you go. Descents in freediving are by necessity much faster than in Scuba so you have to be able to equalise well. Thankfully this has never been an issue for me.

Recovery breathing after a freedive

As I descended, I gazed into the turquoise depths. I love floating in the sea and could look at that colour forever. As I thought about this, I started to feel my diaphragm spasm. I tried to ignore it, knowing that this was natural and expected and predictable and nothing to worry about, but it started to gnaw away at my confidence. I turned around to face the light and started to kick my fins as fast as I could: I really wanted to get up there quickly. My instructor was there with me and grabbed me to slow me down. I was supposed to ascend calmly: being calm reduces the rate of oxygen consumption. Being calm is much safer. On my first descent, I had already hit 13 meters!

Clear Snorkeling waters - Koh Tao, Thailand

We practiced some more that day, and sailed off to a diving site called “Japanese Gardens” to snorkel afterwards. It was fun to swim down to the divers and watch them whilst not wearing any gear myself. The water was beautifully clear.

I had homework to do that evening: reading a manual and writing tests. I was exhausted by the end of the day: it was definitely a lot harder work than scuba, especially since so much time is spent clinging to the buoy in in the waves at the surface whilst “breathing up” or recovering.

I was also pretty badly sunburned. I had only been wearing a short wetsuit and all that time floating at the surface had burned my hands and arms. I had used sunscreen, of course, but it had washed off and left me with a perfect “Trucker Tan”.

The next day I tried again, hitting 19 meters. Whilst the fitness is paramount, the ability to clear your mind and know your limits, despite what your fears might be telling you is critical. I kept thinking things like:

“Do I really take enough air at the surface?”
“What if I drown?”
“I don’t have enough air to go back up!”

But of course, I was fine. In fact I felt as though I didn’t really need to breathe once I got to the surface again: it was clearly just my mind playing tricks. The feeling of being down there with no equipment is a mixture of extreme terror and pleasure in a totally blue surrounding with eerie slience. It is easy to understand why some people become obsessive about freediving – there’s definitely an adrenaline rush to the sport.

Steve, my Freediving Instructor and me

At this point, I was pretty proud of my achievement: it was 1 meter short of my 20 meter goal, but still pretty impressive. I sat a quick test after lunch and passed the course. I always try to get a picture with my instructor, and this was no exception. Admire my trucker tan in the photo above!

Duncan and his Advanced Open Water Instructor

I left the freediving school and walked past Duncan’s Scuba school. He had passed as well, so I got a snap of him and his instructor. We congratulated each other. Before this day, Duncan was not allowed to dive below 18 meters and now he was certified to dive to 30 meters. By comparison, I was allowed to swim in the sea, and now I have passed a course to prove that I can indeed swim in the sea!


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