DRIFTING OVER THE RIOTOUS LANDSCAPE of this sunlit reef and out into the blue water, various questions spring to mind, in no particular order.
What kind of speed-to-mass ratio can lift a 3m manta ray out of the water to crash back down above us in a pentagon of surf
If I let go of this scooter, how long would it take to churn its way 1500m to the seabed And how popular would I be back at the dive centre
Why do these huge, plump, Indian Ocean starfish look like Bart Simpsons fingers
Is there a more head-spinning spectacle than a cloud of glassfish in a cave, a thick soup of ghostly creatures like a vast tapioca pudding with eyes Or the sight of a sting ray sprung from its lair and thundering down a vertical wall, shedding a mist of sand
If legal aid was available for cruelly named sea creatures, shouldnt the brown-blotched sandperch be due some sort of compensation
And behind it in the queue, surely, that gorgeous 6cm nudibranch - black and white-striped with delicate florets of yellow - damned forever to crawl the ocean floors as the varicose wart slug
No matter how multi-coloured they are on the surface, dont all tattoos look blue below 10m And doesnt the person who thought of using toothpaste as a sparkling, mist-free mask-cleaner deserve some kind of a medal
And, lastly, what kind of apocalypse took place all those millions of years ago, when this almighty volcano last blew its top
Darren, our dive leader, was in the Maldives when the last apocalypse hit, the tsunami of 2004. With no warning, the wave that eventually reached these fragile islands walloped into the outer circle of this giant volcanic rim, tearing down beach huts and washing through the palm trees.
By the time it reached Komandoo in the inner circle, it had subdued to just a freak high and low tide. Darren was on the seabed of the house reef instructing a novice when he felt a violent surge above him.
Hed just checked his gauge, and it read 16m. He checked it again, still on the bottom, and it read just over 18m. Some fairly basic mathematics suggested that about 2m of additional water had appeared above him, drowning out the jetty, swarming across two-thirds of this pancake-flat atoll, even flooding the sandy floors of the bars and restaurants.
When it drained back off the neighbouring Kuredu in the northern Lhaviyani Atoll, where Im based for a week, ProDivers manager Ray Van Eeden found himself sprinting to the beach. A collection of daft and unimaginative holiday-makers had leapt onto quad bikes and were charging out onto the exposed strips of unseen land in an idiotic attempt to collect shells.
Today, its hard to imagine anything bar the odd splash of warm, tropical rain ever rippling the peace of this extraordinary place.
You get a ravishing view of the terrain from the taxi that takes you 80 miles from the airport, a twin-prop seaplane steered by two pilots in uniform but with bare feet, very James Bond.
The atolls roll out below you like drops of light turquoise on a watercolour palette of blue.

MOST OF PRODIVERS 45 DIVE SITES feature the magic combination of coral cliffs and the promise of big game lumbering out of the deep. Were too
far north for whale sharks, but precious little else could take the shine off a family of reef sharks, in all sizes, pulsating out of the gloom, or a spotted eagle ray steaming by, with a metre-long hawksbill turtle treading along behind it.
Unless of course, its a cameo appearance by a 2m guitar shark hiding unsuccessfully on a sand spit, a bizarre collection of different-sized triangles hammered down the spine of its flat, leathery body.
Its a creature that flies boldly in the face of the Trades Descriptions Act by being neither a shark (its a distant cousin of the ray family) or actually able to play the guitar.
The legal limit in the Maldives is now 30m depth and 60 minutes duration for any dive, so youre never wrestling with any great challenge. Why go deeper anyway The light tails off, the landscape wont improve, and there are fewer schooling reef fish than in the shallows.
ProDivers now runs a tech course, incidentally, on which it demonstrates the pressure at 30m by breaking an egg: the white drifts away but the yolk can be patted back and forth like a hard yellow ping-pong ball - until the same emperor angelfish, presumably with above-average memory, whips in and swallows it whole.
The highlights come thick and fast on these warm-bath excursions - very fast, in fact, if you catch any of the currents, a new experience for me and one that takes a degree of adjustment.
I know now that if you travel just below a cliff-top you can sail gracefully past the coral wall without so much as twitching a fin. But travel just a metre above, on the plateau itself, and you are permanently paddling against a cross-current, and can gulp down a quarter-tank in five minutes.
On one occasion, we try to cross a dark-blue channel sucking the tide into a light-blue crater, and two of us finish up flapping about gormlessly as were gently swept into the inside.
Not that it matters: were all equipped with marker-buoys, and not expected to regroup at the anchor chain for the final ascent. Divers surface all over the place and are hoovered up by the circling boat, where a glass of sweet tea, some coconut and a slice of seed cake await.
The coral is spectacular beyond belief - better, even, than in the Caribbean, though the visibility isnt always pin-sharp. And there are none of those uneventful slogs across acres of seagrass before you hit the coral-head that you seem to get in the Red Sea.
The walls are absolutely rammed with fragile sculptures of every size, shape and colour. The Orimas Thila dive site is the best, a Mad-Hatters Tea Party of psychedelic mushrooms, featherstars, bright orange sea whips, giant gorgonian fans, and those corals that look like enormous golfballs.
The whiskers of spiny lobsters protrude from gullies between them, and the crooked purple gums of big clams pull shut when you pass, like those cartoon characters with a wiggly line for a mouth. Most exotic of all are the branch corals that attract shoals of little turquoise fish in their protective branches, like a cloud of blue air being inhaled by some bone-like lungs.
El Niño fatally raised the water temperatures in 1998, killing off vast tracts of coral in the Indian Ocean, but the rate of recovery is a joy to behold.
None of the table corals at Orivaru Giri can be more than 10 years old, yet one of these vast pizzas of knotted brown branches is more than 2m wide.
Sparkling new growths have sprouted in this boneyard of devastation. Its shallow here - no more than 16m at most, and the best vistas all at seven - so dead corals have been uprooted by storms and tossed all over the seabed, their stems pointing upwards like overturned tables in a bar-room brawl.
And the fish life is out of this world. Honeycomb morays and the odd striped zebra moray gurn viciously in their
lairs. Oriental sweetlips wander past, apparently on their way to a pyjama party, almost upstaged by the bizarre mottled clothing of the clown triggerfish.
Massive napoleons trundle along, and gorgeous pairs of reef bannerfish. There are shrimp gobies darting back into burrows, and little anemonefish hiding in carpet anemone that looks like a slab of translucent orange tripe.
One of our team clocks up his 20th different shark species on sighting the squat, giant-dogfish contours of a blacktip reef shark.

BUT THE HIGHLIGHTS ARE THE ONES you didnt expect. A shoal of remora fish engulf us, so close that you can see the rough adhesive patches on top of their heads, where they attach themselves to sharks for free food and transport.
And there is the unforgettable sight of an ornate ghost pipefish, only 30mm long - half your little finger - a tiny spectral ribbon of green moss, like a cross between a pipe-cleaner and a seahorse dressed in weed. We found one 22m down on a wreck on the Kuredu house reef, so small and cunningly camouflaged that it took me 30 seconds to even see the damned thing.
And just when you thought you werent getting the full complement of fish and ships, we drop off at two tremendous wrecks (the only dive in 12 we have to share with another boat).
The star turn here is the 35m carcass of a Japanese-registered refrigerator ship that was being towed from the harbour of a tuna factory at Felivaru in 1981 when it caught fire, sank, tipped up against a sloping coral wall and came to rest with its bow jutting out of the water (now crowned with a herons nest).
Its a fantastic sight, above and below water, though even experienced divers get destabilised by its tangle of confusing angles - a ship sloping upwards but tipped sideways, with rails and rigging making even more dizzying dimensions of jumbled geometry.
These and other yarns are exchanged on the palm-fringed decking of the beach bars later, but Kuredu is not a place designed for the post-dive wind-down.
Apart from the occasional crab race, theres virtually no nightlife at all.
The Maldives are famous as a honeymoon destination: Youre going alone, sir the girl at the Gatwick check-in asked me sympathetically, possibly suspecting that Id been stood up at the altar - and the charter has a high take-up for its pre-orders of champagne.

BUT THE RESORT IS EXQUISITELY QUIET and beautiful, only half a mile long, a barefoot island where all the roads - even the floors of the bars and restaurants - are soft white sand, and news of a turtle nest outside Number 308 sparks a swift detour to the beach bungalows, where whispering trees are patrolled at dusk by noiseless fruit-eating bats with a 1m wingspan.
ProDivers is the best-organised centre Ive ever seen. The palm-thatched stone buildings even have four different tanks for washing equipment, and theres a wide variety of courses to keep raising your game.
After a gruelling night calculating decompression times from skull-cracking conversion tables, I graduated to nitrox - a real advantage because:
a) you can always manage a 60-minute dive, b) you dont feel like sleeping for 10 minutes when you surface, and c) youre welcomed into that yellow-tank hardcore on the boat (some of whom, lets be honest, regard 21% O2-suckers as barely a notch up from snorkellers).
Another new experience: an hour with a scooter! Ive always regarded these 2ft plastic turbines as the preserve of jet-skiers and other ASBO-magnets and habitat-wreckers, but theyre outrageous fun, and dont appear to bother the neighbours - in fact, a hawksbill and an eagle ray both returned for a closer look.
DPVs tug you along at a fast walking pace, about three knots - which means very slowly against a strong current - but flip around and go with the drift and, oh my lord, youre flying across the carpet of coral at around six knots.
Its like one of those perfect diving dreams, but in fast-forward. The only disadvantage is that if you slow down, for even an instant, to look at something, the others are gone, and youre accelerating manically towards a trail of bubbles.
I cant recommend Kuredu enough. My abiding memory is of the sheer abundance of fish in the Indian Ocean.
Theres a split-point at Orimas Thila where two currents collide and the whole food-chain gets invited to the party. Thick clouds of plankton are being dispatched by inter-weaving spirals of snappers and batfish, with big old tuna powering in to break off a corner of this candy-striped orgy and turn it into a take-away meal.
You almost feel a part of this feeding frenzy. Theres a barbecued jackfish waiting back up on the boat.

GETTING THERE: Mark Ellen took a Monarch Airlines charter from Gatwick to the capital, Male, then a Maldivian Air seaplane to Kuredu Island Resort.
DIVING: ProDivers, www.prodivers.com
ACCOMMODATION: The hotel has four different levels of accommodation, from beach bungalows (£60 a night ) to water villas (£200 a night), including breakfast.
WHEN TO GO: Its near the Equator, so theres barely any seasonal change. Hot all year, with the odd warm shower. Least chance of rain is in February, March and April.
MONEY: US dollars, but credit card covers island expenses..
PRICES: The return charter flight is £485, air taxis from Male £160 return and 10 dives with equipment rental is US $535.
FURTHER INFORMATION: www.visitmaldives.com