But the physical discomfort is more than matched by anxiety. It's been over a year since I gained my diving qualification - the PADI open water course - and everyone else on the boat is more experienced than I am. A persistent litany of diving disasters learned while training is repeating itself in my head - nitrogen narcosis, decompression sickness, burst ear drums, to name but a few. With all this complicated and uncomfortable equipment on my back, I have the impression that I am doing something we were not really meant to do...
Five minutes later, my fears are forgotten. I am overwhelmed by the sights and sensations of the sea - flying would feel something like this. Effortlessly suspended by the water I have an overwhelming sensation of space. Look up and see the surface of the water way above; look down to the reefs and dizzying chasms below. Shards of sunlight pierce the surrounding blue. Sound is minimal apart from the noise of my own breathing. Trails of silver- grey bubbles float in front of my face. I am in Sharm El Sheikh on the Egyptian Red Sea - one of the world's most famous diving centres. It is also the most accessible from Europe: only just beyond the Mediterranean, but offering exotic marine life.
This is a tropical reef, with a rich and vibrant sea life. Its coral ranges from gently rounded folds and pleats, to spikes, points and branches, and fan-shaped gorgonian corals unfurling like giant brandy snaps along the edge of the reefs. Depending on the coral for sustenance is a plethora of sea-life, from tiny florescent fish to the hulking Napoleon wrasse (so called because of the bump on its head resembles the emperor's hat). Psychedelic splashes of colour flash by in the shape of parrot, butterfly, and picasso fish. Even more exotic are the stingrays, the giant turtles which glide overhead, puffer fish looking as if they are about to explode, and the giant moray eels which poke their heads out from under the rocks, jagged teeth bent into a permanent snarl. I even see my first shark - in fact four nurse sharks - chilling out in a sandy bay. We are assured by our instructors that sharks rarely attack in this area (they are too well fed and are not attracted by divers anyway).
At the start of the week, I am the one who puts the equipment on the wrong way, who bobs up and down because my buoyancy isn't right, and who runs out of air too quickly as a consequence. But when you are diving as part of a course, everybody else is as inept as you are and the instructor makes allowances. By the end of the week I am using less air, my movement in the water is markedly better and, most importantly, I feel relaxed and confident.
My centre ensures that in every five day package, divers get to visit the two most famous sites in the area - Ras Muhammad and the Straits of Tiran. Ras Muhammad is one of the most famous dive sites in the world and has been a National Park since 1983. Situated on the tip of the Sinai peninsula, it is the point where the Gulf of Aqaba and the Gulf of Suez meet. Descending near Shark Reef, I find the sea thick with fish. The reef on the right is home to colourful tropical species while out in the blue, schools of tuna, snappers, and sharks patrol. The reef falls away into infinity beneath you.
The adjoining reef, Yolanda, is also memorable, but for different reasons: the first thing I see is a huge Napoleon wrasse hovering over a lavatory bowl, looking as if he is trying to use it. Looking around, I see that the whole sea bed is littered with bathroom furnishings - row upon row of upturned baths, swathes of shower curtain fabric, and a pile of upturned basins. The reef is named after the unfortunate cargo ship Yolanda, wrecked here in the 1980s.
One thought keeps bothering me during the week - will people diving in 100 years time find the coral and fish in the same condition? The region takes its responsibilities to the marine environment very seriously, having established the Ras Muhammad National Park to monitor diving and fishing in the area, and undertake research and educational projects. The dive centres also do their best - strict instructions are given not to handle fish or corals and crucially, to control your buoyancy so that you do not bump into anything. But the sheer number of divers is alarming. One day, a member of our party, a huge man, lost control and went crashing into some corals. Several hundred years of growth were destroyed in a second. The instructor sent the offender to the surface, but it was too late.
At the end of the week I felt far more relaxed than I think I would have been after seven days on a beach. A combination of indulging in physical activity and concentrating on the natural world works wonders for stress levels.
diving fact file
The author took her diving holiday with Kuoni (Tel: 01306 744345). They have one charter weekly from London Gatwick to Sharm El-Sheikh. A basic package of flight plus 7 nights B&B in a six-bed dormitory is pounds 299; this goes up to pounds 650 per person in double room in a five-star hotel (two sharing). These prices don't include diving expenses - five days diving will cost pounds 129; five days diving including the PADI course will cost pounds 177 plus about US$30 certification. Otherwise try a liveaboard (where you live on the boat) which ranges from pounds 680 to pounds 1000 per berth - full board and all diving costs included.
The different seasons in Sharm El Sheikh provide different conditions. In February and March the weather is a little windy but the extra plankton in the water attracts manta rays. From May to August fish shoaling occurs on a large scale. In November and December the visibility is exceptionally good (up to 70 metres).
Two bodies award diving certificates that are recognised round the world: the international PADI (Tel: 0117 971 1717) and the British BSAC (Tel: 0500 947202). Preliminary certificates from either body can be obtained after five days of diving, and there are further stages leading up to -instructor level. For a preview of the world of diving, have a look at BSAC's "Go Diving!" CD, available in bookshops for pounds 29.95. For a range of colourful and informative books on diving, see New Holland Publishers' catalogue (Call 0171 7247773).