NO, SCUBA DIVING is not only for super-fit swimmers with iron lungs. The silent, weightless undersea world is an exhilarating realm that should be explored by anyone who is reasonably healthy, at least once in a lifetime. Because right next door (ok, maybe a few more doors away) in Sabah's turquoise, watery havens lie some of the top diving hotspots that wow divers from all over the world with its incredible marine biodiversity. We round up the top dive sites in Sabah, each with something unique to offer.

With its sandy sea-beds, shallow depths and gentle currents, Mabul is the perfect place for newbie divers to flex their fins, and more, with a reputation as one of the world's richest spots for small exotic marine life, the critter action here ranges from the cutesy to out-of-this-world weird to plain spooky. Numerous lionfish, pipefish and the resident frogfish in all its warty glory can be seen. At the bottom, a flamboyant cuttlefish, the only species of cuttlefish known to be able to "walk", ambles nonchalantly across the sea-bed. Coming up close with the sinister-looking moray eel, we thought it was just trying to look unfriendly, but later learn that its gaping mouth is necessary for respiration. By sheer luck, we also catch a glimpse of the mimic octopus, which is supposed to be able to morph into the physical likeness of up to 15 species, like crabs, snakes and stingrays. Take that, Mystique. The dive master says that the golf ball-sized blue-ringed octopus can sometimes be seen here, but with its label as one of the world's most venomous animals, we weren't particularly jumping out of our wetsuit to see one. And just in case you need help getting that bit of breakfast dislodged from your teeth, the industrious cleaner shrimps (identifiable by their red and white stripes just like the barber poles!) will service you for free-just open your mouth. Those with keen eyes can also spot pygmy seahorses, which are so small (they're at most an inch long) that they are known to keel over from the powerful camera flashlights of ignorant divers and this entire in just one dive.

While small and weird is the order of the day at Mabul, the celebrated depths of Sipadan is where everyday life plays out like the grandest of operatic shows, as superstars of the marine world strut their stuff in unbelievably clear waters. In fact, this diving mecca is such a treasured nature site that the government has not only shut down all resorts on the tiny island but imposed a maximum quota of 120 divers per day.

Submerged at Sipadan's famous Barracuda Point one early morning, we witness mind-blowing rush hour traffic of schooling jack fish, hammerheads, white tip and grey reef sharks. Massive bump head parrotfish shimmied past in all their effervescent glory. Against terraced walls adorned with corals and gorgonian fans, a hawksbill turtle cast its masked admirers a cursory, melancholic glance before paddling past. Dropping lower, night falls as the sun is momentarily blocked out by a glistening vortex of barracudas, a signature occurrence that gives the dive site its name. Think of this as the New York of the fish world.

Thirty meters down, the action tapers off and so does the light, but like a mountaineer eager to scale the highest peak, I feel the draw to sink to greater depths. Exhaling, I descend a few more meters only to be rewarded with a stab of cold piercing through my bodysuit. Peering beneath me, I am strangely drawn, almost hypnotized, to embrace the murky cobalt of nothingness along with whatever secrets it may hold. It is at this surreal moment where, at the risk of sounding cheesy, I embrace my inner mermaid. A sharp rap on the tank from my dive buddy breaks the spell, and I quickly fin myself up to rejoin the gang.

Mataking has admittedly seen better days, no thanks to illegal fish bombing, a method used by fishermen to mass-harvest ornamental fishes but fortunately, intensive conservation efforts such as coral reef farms, turtle hatcheries and even shark feeding programs have resuscitated its seascape. Given its history, we were thus amazed to find a flourishing community of mar - life just off the house reef at The Reef Dive Resort (the only resort on the island).

This is one place where it pays to stick real close to the dive master as the marine cuties here share a skittish tendency of darting in and out of their hiding holes-untrained eyes will not be able to spot them quick enough. And right under the resort's jetty, big eye trevallies and batfish congregate. If you happen to pass by early in the morning around Gam, you'll be able to catch hump head parrotfish asleep, hanging motionless in the water with their eyes wide open.

Mataking also claims fame to having the highest number of spotted groupers in its waters. The Mataking I wreck, an artificial reef that doubles as an underwater post office is a must-see. No wonder it's known to be one of the best jetty dives in the whole of South East Asia.

Diving aside, you'd want to save some energy for a night trek, because come nightfall, the island's forest springs into action, with coconut-sized coconut crabs scampering about for food, fireflies glimmering in the dark and sometimes exotic seabirds flying by. Sitting far, far out into the Celebes Sea and off the dive junkie's radar, Mataking is also excellent for those who want some privacy and pampering. The luxurious jamu spa massage is heavenly after a long day of diving, but our favorite is the outdoor Jacuzzi where you can bask in the sunset with a drink in hand... definitely honeymoon material.

Part of the Sugud Marine Conservation Area, the live coral island of Lankayan offers a double treat to guests who wager a visit to its lesser-known shores-postcard-perfect, palm-fringed beaches with azure waters that belie the monstrous beauties beneath. At one of its best dive sites, Jawfish Lair, lies one of the underwater photographer's favorite subjects-"pregnant" jawfish carrying a batch of eggs in its cavernous jaws. Interestingly, the jawfish found here are mostly about triple the size of their usual length (4-5 inches). Lankayan's highlight, however, is an up close and personal encounter with the world's biggest fish, the whale shark. This almost sacred experience is not a guarantee but your best chances of spotting the gentle behemoth is highest in April and May when it makes its annual migration past the island.

At night, leopard and black tip reef sharks come right up to the shallow parts of the water underneath the dining decks, and the spectacular sunsets and stunning twilights (when there is a full moon, especially) provide ample Kodak moments for shutterbugs. Further into the night, we witness another slice of nature at its most beautiful yet heart-rending-that of watching 45 newly-hatched baby turtles running the make-or-break race of their lives into the sea. If your entourage consists of both divers and non-divers, Lankayan is definitely a great bet.