In search of an unspoilt underwater paradise, Kate Hodal dives into the colourful waters surrounding the island of Tenggol.

By Kate Hodal The minute I topple over the side of the boat in East Malaysia, I know everything has changed forever.

Below me glimmers a shoal of white and turquoise fish feeding on shallow coral. To my left, an angelfish flits around my fins - its electric blue, yellow, purple and orange markings glow in the early morning light.

While I have good reason to be splashing about in these warm turquoise waters, a hotspot for marine biodiversity, nothing prepares me for what I see next.

Pressing my mask down into the small waves, a bustling aquatic city comes into view. Schools of coral and blue groupers zoom past as leopard-print Andaman sweetlips munch on floating plankton, like a large family sitting down to a communal meal.

A group of Moorish idols - the punk rockers of the fish world with their yellow-black mohicans - window-shop in pairs, gazing at the corals branching out like long fingers amidst the sea ferns wavering back and forth.

There are fish courting, eels gliding, reef sharks darting, turtles drifting, and then there's us: a small group of divers from around the world, floating amid this scene of staggering beauty.

Still a novice at this whole scuba-diving business, I have only recently earned my PADI Open Water certificate and have logged just a handful of dives to date, most of them in Mexico.

But because half the world's species live in our oceans, and I'm forever curious to see how other halves live, I've swapped the grey skies of London for a four-day underwater tour of eastern peninsular Malaysia, a magical land a full day's flight away. Now, decked out in my short wetsuit, all I can say is, if it weren't for my oxygenated mouthpiece, I'd be breathless.

There are more than 20 dive sites around Tenggol, an island roughly 50-hectares in size just off the coast of eastern Malaysia, dotted with thick jungle jutting out into the bright blue sea.

Said to be one of the last unspoilt islands in the region, Tenggol was voted Best Diving in Peninsular Malaysia by Asian Diver Magazine in 2002, with deep-sea and wreck dives some of the most popular.

This is a place where average visibility hovers around 20m and its preponderance of rare species make it one of the most rewarding dive sites in the country.

Most enthusiasts head to Malaysian dive sites such as Sipadan or Langkawi, or even to Phuket and Phi Phi in Thailand, but I can't believe there aren't more people here.

Having flown from London to Malaysia's capital, Kuala Lumpur, then taken a quick one-hour flight east to Terengganu, our schedule for our four-day getaway is two dives per day, with a break in-between for a barbecue of locally-caught grilled fish and squid, fried rice with veggies, and teh tarik, black tea sweetened with condensed milk.

Our divemaster, Richard, kills my pre-dive nerves by reminding me of the basics ("Breathe normally and enjoy yourself") and promises to keep a vigilant eye on me and my 'buddy', a Chinese girl who has come to Malaysia for the weekend and who will be serving as my diving partner.

As we're a motley six-man bunch of novices and pros, we avoid the wrecks and head instead for coral balconies and popular aquamarine hang-outs.

Each dive is more stunning than the last. At Tokong Timur, a 22m descent along a boulder outcrop, I decide I want to be a mermaid and start doing somersaults.

I'm so happy. There are forests of seaweed interspersed with brain, anemone, whip and honeycomb coral, surrounded by blue-spotted stingrays, humphead parrotfish, giant clams, surgeonfish, barracudas and hawksbill turtles. I feel like my heart may explode.

"I've never been diving where the only people you see are in your own group," says my dive buddy Lisa as we lunch on grilled squid and local fruits on Tenggol Island. "I've logged around 150 dives in the Philippines, Thailand and Indonesia, and you're always competing for space with other divers at the dive sites. To be alone like this is really amazing."

And Richard has been diving all over the world - from shipwrecks in the Red Sea to tourist hotspots such as Phi Phi in Thailand - but chose to live and offer diving courses in Malaysia because he'd never seen anything like it.

"The diversity of coral and vitality of sea life make this place unique - and the fact you can almost guarantee there won't be anyone else in the water apart from you and your group, is almost unheard of," he tells me as we head back to base in the speedboat after a long day at sea.

"When you dive in places like Phi Phi, you'll be diving with six other boats, so you may see more divers than fish."

While it is possible to stay on Tenggol - there are three very basic campsites-cum-DIY-huts - I've opted instead for a luxurious cabana at the Tanjong Jara Resort on the mainland.

The gorgeous compound is designed like a 17th-century Malay palace and set right on a powdery white beach lapped by shallow turquoise waves, fringed with shady palms.

Popular with honeymooners who wander the grounds hand-in-hand and gaze out at the sunset with cocktails, it's the perfect place to come diving. The resort offers a range of certifications and courses, all taught by Richard. After a long day of diving, I look forward to a cocktail by the pool with my boyfriend.

Not a fan of the underwater world, he whiles away the days taking a crash course in Malaysian cuisine, long walks in the jungle and longer sessions at the massage table.

He fills me in with the "news" whenever I return: how the hotel staff warned him, once more, not to leave his shoes outside the cabin as "monkeys will steal them", or how delighted he was to see a 5ft-long monitor lizard taking an early morning dip in the pool.

"It's his daily exercise," the pool boy had explained, laughing, urging my boyfriend to dive in once the lizard was done. "He won't be long now."

The resort is well known for its cuisine and health centre, so one afternoon, post-dive, I indulge in a "princess massage", named after the pre-marriage rituals provided to Malaysian monarchy.

It starts with a bath of gardenia, honeysuckle and bougainvillaea petals, followed by a hibiscus scrub and hibiscus-oil massage.

Later that night, as my boyfriend and I watch the ochre dusk fall into night, I feel more peaceful than I have in years.

As we celebrate our last night dining outdoors on deliciously crispy buttermilk prawns served with coconut water and sauteed bok choi - chef Anne having provided a "talking menu" to describe each meal to us - we listen to a group of musicians playing the gamelan, a set of 10 brass pots reminiscent of a Southeast Asian calypso.

Families and couples lounge in the open-air cabanas by the water as we take one last stroll down the moonlit beach. When a shooting star glides overhead, I make a wish.

I may have to wait some time before I turn into a mermaid and am sent back to sea, but it's always good to dream.

Travel facts Kate Hodal was a guest of Tanjong Jara Beach Resort, which offers a Diver's Escape package including three nights accommodation, breakfast, two days of diving, and barbecued lunch for each day, starting at MYR 980 (£197) per room per night. Flights to Kuala Lumpur from London are around £790 on Malaysia Airlines. The dive starts again on March 1. Visit www.tanjongjararesort.com