You may have 'met' Jacki Ng underwater if you are an avid diver. After all, the 31-year-old diving instructor has gone on close to 2,000 dives in the last 10 years, in places from Singapore's Pulau Hantu to Manado in Indonesia.

He's not alone in taking the plunge. Based on anecdotal evidence and checks with dive schools here, more and more Singaporeans are packing their scuba masks and flippers and heading to regional dive sites.

Underwater paradise: Even though the surrounding waters drop to a 2,000m-deep abyss, the breathtaking corals and marine life in Layang Layang, 300km off the coast of Sabah, are a diver's delight.

One of them is Ms Toh Pei Shiang, 33, an assistant advertisement and promotions manager who started diving in 2004. She counts Hindeang in Thailand and Pulau Perhentian in Malaysia among her fave destinations.

The catch for these enthusiasts: A chance to have close encounters with reef sharks, swim among colourful fish and marvel at corals and other marine life.

Mr Ng, a diving instructor at Gill Divers in Tanjong Pagar, says divers plumb the depths abroad because 'Singapore is a port city and the waters around it are not perfectly clear'.

The numbers who venture overseas are enough to make a big splash. Mr Stephen Beng, president of the Singapore Underwater Federation, says there are 10,000 active certified divers here who do so every year.

'Divers travel within Asia because the dive sites are situated within the Ring of Fire, where volcanic activity ensures the largest diversity of marine life,' adds Mr Beng, 37, who has chalked up over 4,800 dives since 1989.

He notes that Indonesia's dive sites are widely considered to be the most biologically diverse in the world.

The good thing about diving is that you need not take leave from school or work to indulge in it - unless you're jetting off to faraway Fiji, the Bahamas or the Caribbean.

A dive trip is relatively easy to plan as a weekend getaway in nearby Malaysia, Indonesia, Thailand and the Philippines.

Mr Xu Renhan, 25, a production assistant at sports channel ESPN and divemaster at The Submersibles, says: 'I always thought of diving as an activity to do on a holiday, but I have found that it's something you can do whenever you feel like having a weekend away from here.

'You don't even need to go with a group of friends. You can go to foreign places and meet new people,' adds Mr Xu, who has gone on 193 dives since he first slipped on his flippers in 2002.

Ms Stella Lee of Waikiki Dive Centre, a 13-year-old outfit that organises trips to regional waters, observes that diving can be enjoyed as a family outing or as an opportunity to meet new friends.

'You also get to travel to different countries and experience their local cultures,' she adds.

It is no wonder then that diving as a recreational sport has been gaining buoyancy.

See me fly: Turtles may be slow-mo on land, but in water, they can glide very fast.

Dive operators and instructors tell Life! that the number of Singaporeans taking dive courses and getting certified, mostly by the Professional Association of Diving Instructors (Padi), has increased in the last five years.

Mr Ng, for example, has seen a year-on-year increase of about 10 per cent at his dive centre since 2002. Last year, it had about 500 people signing up.

Waikiki's Ms Lee reports a 50 per cent increase in the number of students certified - from 222 in 2005 to 327 last year.

And once you take the plunge, divers say, you are addicted for life.

Ms Toh, who first went underwater in December 2004, says diving was initially something she wanted to experience just once in her lifetime - but she was 'hooked after the first try'.

'You will start looking for different marine creatures and you will always find new things. Every dive is different - that's where the thrill comes from,' adds Ms Toh, who has recently taken to diving with a magnifying glass to spot the smaller fish.

Says undergraduate Timothy Chen, 23, a newcomer to the recreational sport: 'The most fascinating thing is how diving forces you to relax. There's nothing much you can do except breathe.

'Apart from that, you also get to see the spectacular marine world.''

Not cheap to dive

To be sure, diving is not a cheap sport. First, you have to take lessons and be certified before you can go on dive trips unsupervised.

Initial costs for an open-water course range between $400 and $700, with the average hovering around $550. It includes two pool and six theory lessons plus four open-sea dives.

A two-day trip to nearby Tioman in Malaysia costs about $300 for ground and sea transport, accommodation and equipment for five dives.

It can go up to about $800 for a four-day-three-night trip to the Philippines - inclusive of return airfare, accommodation at beachside resorts and five dives.

These forays can be easily arranged independently of travel agencies - all you need is a Padi certification and passport. You can take your own equipment, or rent from on-site operators.

Some places take more than a mild inconvenience to get to. Once you get to Hindeang in Thailand, for example, you will be staying on a boat for the duration of the trip, as the dive spot is very far from the coast.

But the hassle is worth it, says Ms Toh, because the water is very clear, with visibility of 20m to 30m on a good day, and you can see many manta rays.

Ultimately, diving is a non-competitive sport that is about appreciating the beauty of the underwater world, says Ms Esther Lee, a dive instructor at The Submersibles.

Mr Ng agrees, saying: 'In Manado, Indonesia, for example, you can see the mimic octopus, so called because it mimics colours of the reef, and actions of other marine animals. There is also an electric clam that lights up.'

Mr Xu has his fish stories too.

'In Sipadan in Malaysia, there are schools of reef sharks, cyclones of barracudas and walls of fish so thick you can't see through them.

'Not to mention the very ugly but always fascinating frog fish.'

With the monsoon season just over, divers are putting on their flippers again. While Malaysian dive spots Tioman, Redang and Dayang remain popular, divers say it's worthwhile to take some roads - or seas - less travelled to catch the, well, bigger fish.

Mr Stephen Beng, president of the Singapore Underwater Federation, stresses that divers should do research before heading out. Dive centres are the best resources because they know first hand most details about the site, and instructors can advise you on environmental conditions underwater, he says.

Here are six favourite spots to flip for.

1. Sipadan, Malaysia

Why: Made famous by Jacques Cousteau's documentary, Ghost Of The Sea Turtles, this island is the only oceanic island (not connected to the continental shelf) in Malaysia that rises 600m on a limestone pinnacle and 'mushrooms' out near the surface.

Not only are there fascinating coral structures but there are also marine caves.

Pulau Sipadan is reported to have the largest variety of soft corals in the world. Turtles swim and frolic freely in the waters around Sipadan and divers will find lobsters, barracudas, beautiful coral fish and sometimes even sharks swimming by.

Flippers in a flap: Male green turtles fighting over a female in the waters of Sipadan, Malaysia.

Depth: 15 to 20m

Visibility: At least 30m

Getting there: 45-minute speedboat ride from Semporna port in Borneo

Best months: Diving can be done all-year, although January to March can see some stormy weather.

2. Manado, Indonesia

Why: The city of Manado in northern Sulawesi is usually regarded as the gateway to the world-class dive spots in the Bunaken National Park, the Lembeh Strait and a number of islands further out.

Muck diving - diving for little critters on the seabed - is usually the norm in Manado bay with a wide range of critters to be found for the eagle-eyed diver.

Extraordinary walls and vertiginous drop-offs abound at this dive site, which is also rich in corals and reef fish, including feather-stars, sponges, nudibranches (a type of sea slug) and gorgonians (sea fan coral).

In several diving spots, turtles, jack-fish, barracudas, napoleons, white and black-tipped sharks can be observed. There is even a well-preserved shipwreck from World War II.

Depth: 5 to 40m

Visibility: 20 to 40m

Getting there: Fly to Manado International Airport

Best months: Every month

3. Cebu Islands, Philippines

Why: Cebu Island is a long narrow island surrounded by 167 neighbouring smaller islands, including Mactan Island, Bantayan, Malapascua, Olango and the Camotes Islands.

At Malapascua, divers can see thresher sharks, Mandarin fish aplenty and some interesting wrecks.

Capitancillo Island has a wall on its south side with gorgonians and other coral formations. Manta rays, yellowfin and groupers are regular visitors and you will also see a good selection of smaller reef fish.

Gato Island, further north, is a good site to see sharks. There is a cave that runs underneath the island which is certainly worth a visit, although it is inhabited by sharks and sea snakes.

Depth: Average of 30m

Visibility: Up to 40m

Getting there: Three hours north of Cebu City by road. Transfers to sites can take up to an hour by boat.

Best months: November to May

4. Similan, Thailand

Why: Located off the coast of Khao Lak or around 100km north-west of Phuket, the Similan Islands comprise nine granite islands covered in thick tropical jungle, surrounded by powder-white beaches and crystal-clear waters.

The area is a protected national park and camping is allowed on the islands. Below the surface lies a diverse landscape of deep canyons, giant boulders, coral gardens, caves and walls. Diving is almost always done off liveaboards - when you have to stay on the boat - that run out of Phuket or day trips from Khao Lak.

Depth: 5 to 30m

Visibility: About 40m

Getting there: Three-hour boat ride from either Phuket or Khao Lak.

Off season: July to September

5. Layang Layang, Malaysia

Why: A breathtaking coral atoll that lies 300km off the coast of Sabah, Layang Layang is part of the 600 island, reef and shoal group in the South China Sea known as The Spratlys.

The pristine coral reef atoll is 14 sq km wide and its surrounding waters drop to a 2,000m deep abyss.

Massive numbers of barracuda, jacks and the hammerhead shark frequent these waters. The reefs and walls are also home to some of the finest and most spectacular displays of hard and soft corals in the world.

Depth: 2,000m

Visibility: About 50m

Getting there: One-hour flight from Kota Kinabalu

Off season: November to January

6. Tulamben, Bali, Indonesia

Why: The Liberty wreck - a United States Army transportation services ship that was torpedoed by the Japanese on Jan 11, 1942 - marks Tulamben as Bali's most famous dive site. The wreck lies in depths from 9m to 30m over 120m of the sea floor, and divers can see the guns, toilets, boilers and anchor chain among other parts of the sunken ship.

It is totally encrusted in anemone, gorgonians and corals.

The marine life includes a huge school of big-eyed trevally and over 400 other species of fish, including anglerfish, neon nudibranches, ghost pipefish, shrimp, goby, garden eels, multi-coloured anthias and butterfly fish.

Don't miss the Tulamben Wall, which drops to over 60m and houses a magnificent purple gorgonian sea fan over 2m wide.

Depth: 5 to 60m

Visibility: 10 to 25m

Getting there: 10-minute boat ride from Amed on the south-eastern tip of Bali

Best months: April to October