I am a certified scuba diver, and before I ever tried freediving I was convinced there was little difference between the two styles. In fact, if anything, I thought freediving would probably be a lot easier. After all, you don't have the hassle of having to assemble and operate the scuba equipment when all you put on, apart from you swimsuit, is a mask and fins.

When a friend kept telling me how amazing freediving was, I was skeptical. When I dive with scuba equipment I can stay underwater for 30 to 45 minutes exploring the depths; but if I freedive, I can stay there for only two minutes at most, so what exactly am I going to see?

With all these reservations I traveled to Thailand's Phuket island during the recent mid-Autumn festival. My mission: to find out what the big deal was.

I registered for a three-day beginner course with We Freedive, a school near Chalong pier run by Richard Wonka, a German, and Sarah Whitcher, a Briton.

The first thing I thought I would learn was how to dive into the water, but on the first day Wonka sat down with me in a classroom and talked about breathing.

"Why do you think you want to breathe?" he asked.

"Well, isn't that because we need the oxygen?" I shot back, assuming it to be logical.

Then Wonka put on my finger a sensor to reads the oxygen saturation of my blood.

"Normal people's oxygen saturation is about 95-99 percent," he said.

He let me inhale and exhale, and the figure never dropped below 95 even when I held my breath for a while.

Wonka said that the urge to breathe comes from the brain's response to the rise of CO2 in the body, and we can train ourselves to get used to high CO2 levels and use body reactions to gauge when we really need to get more oxygen.

"For most people, breathing is something that just happens; for freedivers, breathing is something we choose to do or not to do," he said.

After the classroom session, Whitcher took me to a swimming pool to try out static apnea, meaning to hold my breath while holding still in water. Relaxed, I took a full final breath, put my head in and closed my eyes.

As never before, I became aware of my body and sensed its every part. I became uncomfortable, wanting to breathe, but I chose to withstand the temptation.

On the second attempt I held my breath for 3 minutes and 8 seconds, a personal record, nice and easy.

Later, Wonka taught me how to kick with fins, and let me try dynamic apnea, or swimming horizontally underwater. I surprised myself again by covering 50 meters with one breath.

On the second day we went into the ocean. It was windy and the waves were strong. After we splashed into the water, Wonka dropped a line and taught me how to duck dive, vertically. I then applied the skill I learned the previous day to kick myself down along the line into the depths.

The strong waves made me seasick, and I couldn't focus on myself. I was disoriented in the ocean, couldn't keep my body streamlined and forgot to equalize properly to make the air inside my ear balance with the water pressure.

I was nervous and exhausted and ended up totally frustrated because I failed to dive deeper than 10 meters.

On the third day Wonka took me to a diving pool. In the calm water, the peaceful feeling of being able to focus on my body came back. After adjusting some of my posture I was able to dive perfectly.

At one point I was so engrossed in myself that my head hit the bottom hard.

That was the time I realized that freediving is, as a British freediving instructor Emma Farrell put it in her book One Breath, an exploration not only of the external oceans of our planet, but also the internal ocean of one's self.

And it feels amazing indeed.

(China Daily European Weekly 11/04/2016 page16)