Enjoy a sport with real depth.

It's wet, it;s wild and it's wonderful. Jo Shaw takes a deep breath to explore the fascinating underwater world of scuba diving.

Thirty metres under water there's not a sound to be heard apart from your own breathing. No stress, no hassle, just peace, quiet and another, alien world there to be discovered. You turn slowly to take in the watery scene of brilliant colours, but it's continually changing. Kelp forests, soft corals and crustaceans. Dogfish, haddock, plaice, flatfish, wrasse, even octopus float by in slow motion. Unbelievably; you're in the North Sea. The way Martin and Sharon Ainsworth describe it, it's hard not to fall in love with the idea of scuba diving. And with a little help from the husband and wife team behind The Deep Dive School, it's almost as easy to learn how to do it for yourself.

Martin says: "It's fantastic, because diving is a great equaliser. Contrary to popular belief, you don't need to be super-fit, you just need to be able to swim. Everyone is weightless underwater." Eight or 80, able-bodied or not, a trip to dive school is all you need to set you well on the way to taking that life-changing first breath under water. And Martin and Sharon say once you've taken the plunge, you'll never look back. Diving has become so ingrained in Martin's life, he can barely remember a time he didn't do it. He says: "1 think it all started when I walked past a dive shop and I saw all the sparkly shiny toys in the window. I was smitten."

If you fancy having a go, as a beginner you don't need to worry too much about the "shiny toys". All equipment, from wetsuits, masks and flippers to breathing regulators and tanks is provided with your lessons. If you find you've got the bug, a trip to the couple's shop in Craven Street North, east Hull will have you fitted out with your own gear. The type of suit you will need depends on where you plan on diving. If you're in warm, tropical waters, you will only need a 3mm neoprene wetsuit. If you're diving in the UK in summer, you'll probably need a 6mm semi-dry suit. If you want to dive in the UK during colder weather, you should invest in a full dry suit, hood and gloves.

Thankfully things have improved by fathoms since Martin started learning to dive. He says: 'Years ago, before I really knew what I [was] doing, a few of us went for a dive to Stony Cove, which is now a dive training centre in a quarry near Leicester. Back then it was full of old cars and junk. We had hardly any equipment, just a regulator and a gauge, and went down to about 35m." Sharon takes up the tale from here. "Do you ever get the feeling someone's not telling you the full story?" she asks.

"What really happened was an uninformed dive shop sold him lO-times as much lead weight as he needed. He had no air supply and, being a big lad, he rather quickly dropped to the bottom of the quarry. Of course, he had far too much lead weighing him down, but instead of throwing it away so he could swim to the surface, he somehow climbed up the side with it all still on him."

Martin survived for Sharon to tell the tale, but he's happy for his rookie divers to laugh and learn from his mistakes as long as they don't risk making any of their own. He says: "Safety is always the top priority for us. It's important people realise when they learn to dive with us, it's always in a safe and controlled environment." And in the 16 or so years he's been enjoying scuba diving, Martin has gone from rather over-enthusiastic amateur to join the creme de la creme of dive instructors qualified to teach at the highest level in the world. He's worked his way up the ranks of professional diving, from dive master, to assistant instructor, instructor, master instructor, and is now a PADI (Professional Association Divers International) course director, which means he can teach master instructor courses here in Hull.

Sharon is a marine biologist, and in between the dive school and shop, somehow manages to find time to work on her PhD and teach with Martin at the University of Hull, providing the city's first approved degree course option in dive training. She says: "My hobby turned into my work. It's something I'd always wanted to do, but now we've grasped the opportunity with both hands." The couple ran and worked in dive schools for almost 10 years before setting up shop in east Hull in January 2001 and later joining forces with The Deep. In teaching some of the tourist attraction's aquarists and supplying it with dive equipment, The Deep receives the benefit of Martin and Sharon's diving expertise, while the couple feels the benefit of The Deep brand name.

To qualify to dive at PADI dive centres all over the world, you need to complete an open water dive course. This should take five days, and you can even take theory lessons against the inspirational backdrop of The Deep's floor-to-ceiling tanks of sharks and rays. The course also includes practices in a local swimming pool and open water dives at inland dive training centres such as Stony Cove. First-timers can test the water with Saturday afternoon taster sessions at Winifred HoltbySchool swimming pool, in Midmere Avenue, Leads Road.

Sharon says: "Most people are nervous at first. Breathing under water is not a natural thing, but, we start by showing you how the equipment works on the side of the baths, explaining the signals we use under water, and how to breathe with the regulator in your mouth. Then we move into very shallow water." The training pool depth ranges from a reassuring 50cm to 3m. She adds; "It's great for teaching people. We get a load of toys out and have a laugh, and we find most pupils learn how to use the breathing equipment under water without even realising they're doing it. Then we get them to put their face in the water and breathe, to give people confidence." Martin adds; "I could teach at master level all the time, but to see someone's face when they dive for the first time that's what makes me happy" Once you've learned to dive, you're eligible to join the Deep Dive Club which runs regular trips in the UK and abroad as well as other social events.

In April, it's running a treasure hunt dive at Stony Cove, in May, a club diving holiday to the Red Sea. Martin explains: "My favourite is wreck diving - there's one wreck dive site in Scotland called Scapa Flow, where you can dive around battleships that are sunk in about 45 to 5Om of water. I can remember descending while being surrounded by a mass of steel. It really takes your breath away; " they've dived hundreds of times, all over the world, but ask Martin and Sharon where their favourite dive site is and they answer in unison: "Mayathila, in the Maldives."

Martin explains: "It has a coral outcrop and it's a really special place. It was the first time either of had ever seen sharks on a dive. We went there for the first time in November 1994. The day we got home, I rang up and booked to go back the following April.

The water temperature was about 27C, on land it was in the mid-30s. "There was a 'no news, no shoes' philosophy; which we both loved. It was the flrst holiday we'd ever had where two weeks seemed like a month. You'd no option but to relax. It really was paradise." Sharon adds: "You can be sat in a couple of inches of water and there'll be clownfish and damselfish swimming past looking at you. The only structure to our day was diving. We saw white-tipped reef sharks which came to have a look at us because they were intrigued by the bubbles."

"Last summer, we went to British Columbia in Canada where we saw orcas and whales. Diving in Britain is magical in its own way too." Sharon sums up the appeal: "Diving is a humbling experience. You're at one with nature, it's a fantastic opportunity to share a space with marine life, which allows us to sit and observe. "It upsets me so much when you see evidence of pollution such as untreated sewage being put into the sea. "But it's so quiet under water. Nothing's ever choreographed and nothing's ever the same as the last time you looked. Anything could appear and anything could happen. It's a completely different experience to anything you've ever known."