There is a paradox to being 20 metres under the ocean. It is a place of calm and wonderment. I am immersed in a foreign world, with a new watery sky above me. There is a sense of serenity, blissful peace as countless colourful fish glide past.

Only the tranquillity is deceiving. As a novice diver, my mind ticks over in hyperdrive. All that stands between me and an agonising fate is the tank of oxygen on my back (and, hopefully, the dive guide’s spare air).

There are suddenly a hundred things to remember. A library of complex hand signals, from those that communicate an animal sighting (lionfish – interlocked hands with fingers wiggling) to the essential (out of air – hand moving rapidly across the neck). My dive time and depth, critical to staying within the no-decompression limit, to avoid the risk of life-threatening decompression sickness. The location of my buddy; and, if they stray too far, a stern signal reminder to stay close – both index fingers bumped together.

Hence the paradox: scuba diving is at once liberating and serene, and a challenging comprehension test. Funnily enough, the latter makes the former all the more enjoyable.

Two years ago I decided to learn to scuba dive. There was talk of a family holiday to a renowned........

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