Fear of drowning soon gave way to awe, as amazing scenes unfolded in front of me. I felt as though I had dropped through a watery ceiling into someone else’s universe, populated by a weird and wonderful cast of thousands. There was so much to see, so many bright colours, fabulous plants and strange fish.

Even now, many years later, I still have a sense of wonder at leaving the surface world: it’s a glorious feeling, that first dive of the trip. You may have travelled thousands of miles to reach your destination, or you may simply be diving off your local beach. Either way, the point of your preparations becomes clear as soon as your field of vision changes from sky to sea.

Scuba diving is now one of the most popular holiday activities in the world, with around twenty million qualified divers worldwide. As diving has grown it has also become clear that its success is due to something else apart from being simply a sporting challenge. Diving conveys you effortlessly into another dimension, a liquid world of fabulous habitats and bizarre, wonderful creatures. This other dimension exerts a magnetic influence, which draws people back again and again to plunge into the mysteries of the sea.

But diving has another side to it as well. Recently we have seen the development of a new approach that emphasizes the spiritual side of being underwater. It has been called Zen diving, spiritual scuba, aquatic yoga, yoga scuba and yoga diving, and has inspired courses in places as far apart as Egypt, Mexico, Turkey and the Caribbean.

This movement began in the Red Sea resort of Dahab, with instructor Monica Farrell. Monica is an advanced technical diving instructor and, significantly, she also studied yoga in India. “I began by trying out yoga techniques in my diving classes,” she explains. “I noticed straight away how the asanas [yoga postures] helped with general fitness as well as making people relaxed and helping to cope with the skills that you need to learn”.

Thus was born yoga diving: “My experience is that your ability to stay in the moment – the blue, the colour, the fish, the feeling of floating, your own breathing – that experience of being in the present can be heightened,” explains Monica. And whether you’re freediving, snorkelling or on scuba, the essential idea remains the same: namely that being outside your normal environment can release the mind and enable you to connect with your inner self.

We all know this feeling, the sense of well-being that comes from floating effortlessly in a warm blue sea, marvelling at all the fish swimming around beneath you. So you don’t have to be into new-age spirituality to enjoy the benefits of super-relaxed diving. The best divers are already in a Zen-like state: calm, controlled and centred on the experience.

Another benefit is that it also helps you get closer to fish. Steve Schultz, who has developed a PADI specialty called Mind, Body, Spirit Diving, believes that fish can tell if divers are more relaxed. “Changes that occur when you are in a higher state of consciousness include slower, smoother breathing, slower heart rate, lower blood pressure, and less muscle tension”, he says. “Some of these things fish can sense with their eyes and lateral line sensory systems. When you appear relaxed and in control, fish see you as less of a threat and approach you more”.

Once you have mastered the technicalities of scuba, being relaxed underwater is perhaps the most important skill to learn. The bonus is that it also allows you to appreciate and enjoy marine life when you’re down there – and that, after all, is why we go diving in the first place.

• The Red Sea - An Aquatic Paradise