MOZAMBIQUE HAS ONE OF THE LONGEST COASTLINES IN AFRICA, stretching some 1850 miles from north to south. The southern islands of Inhaca and the Bazaruto archipelago are well-known to divers who cross the border from South Africa, but the logistics of reaching the northern coast have made it virtually inaccessible - until now.
Its still not that easy to get to. After an 11-hour flight from London to Johannesburg, I took another flight to the Mozambican capital Maputo, and then a three-hour flight to Pemba before making the final hop in a helicopter to the tiny island of Vamizi.
Here, I had been told, there was excellent diving on unspoilt coral reefs. After that journey, I was desperately hoping not to be disappointed.
If you like your tropical islands to be small and beautiful, Vamizi wont let you down. Its a thin crescent of thickly forested limestone seven miles long with glaringly bright sand all along its northern-facing coast. Protected by a wide barrier reef, the island is covered with acacias and hibiscus and fringed with wispy casuarinas.
The lodge consists of just 10 wooden villas, all tucked discreetly into the trees and back from the beach so as not to disturb nesting turtles. Inside the villas are king-sized beds draped with muslin mosquito nets - though the island is malaria-free - and instead of windows there are traditional East African wooden latticed shutters that give shimmering views of the cobalt sea.
This is never going to be a mass-market destination, so the chance of the diving boat being crowded is virtually nil.
On my first dive we went to Tuki Point, where Luis Cardoso, the dive guide, led me across a shallow plateau covered in healthy hard corals.
Longnose butterflyfish and vivid blue surgeonfish went about their business of plucking food from the tips of the coral.
As we reached the drop-off, things changed, and I noticed that many of the coral heads bore the marks of bites and scrapes, white scars on the surface of the Porites colonies and chunks taken off the stout tips of the Pocillopora.
Dropping over the lip of the reef wall, I saw why. Humphead parrotfish with their massive beaks were chomping their way along the edge of the reef like a herd of grazing cattle .
Snappp. Cluunkk. I was close enough to hear the 4ft-long fish biting down on the corals. Hovering close to the wall, I waited for the humpheads to pass.
Astonishingly, there were between 90 and 100 of the grazing giants. I have seen humpheads before, and once in Seychelles thought myself lucky to see a group of about 40 individuals.
Successive dives on Vamizis inshore reefs allowed me to see that in most areas the coral and the fish life were in excellent health, something of a rarity in much of the Indian Ocean today.
Vamizi has one major problem: no natural water supply. For tourists, the lodge has its own desalination plant, but the lack of water has meant that very few people have tried to settle here.
However, during Mozambiques long-running civil war (1976 to 1992), some people moved from Cabo Delgado Province to escape the fighting.
These settlers must either sail five miles to Olumbe town on the mainland to collect fresh water, or else buy water from traders who bring it by dhow.
Money from tourism development on Vamizi is already finding its way to the villagers, used to build a clinic, supply medicine and buy books for a school. Villagers have also been employed directly at the lodge, and fish is bought from local boats whenever possible.
One of the challenges for Vamizi in the longer term will be to develop a strategy that allows the villagers to fish the reefs and yet preserve them.
Conservation goals mean that Vamizi is not just a luxury castaway retreat. Other islands in the Quirimbas have already been grabbed by developers wanting to capitalise on the growing Mozambican economy, but Vamizi is part of a more ambitious scheme.
Owned by a syndicate of private investors, the island forms part of the Cabo Delgado Biodiversity Project, aimed at conserving 33,000 hectares of savannah on the mainland and two other islands close to Vamizi.

FOR ALMOST FIVE YEARS, in collaboration with the Zoological Society of London, researchers have been studying the mainland reserve, the three islands and their land and marine eco-systems. Turtle populations have been counted, tagged and protected, and more than 350 reef fish species have already been identified, at least a fifth of them not recorded previously in Mozambique. Hawksbill and green turtles both use Vamizi for nesting sites, and building the lodge has meant that no-one can now steal their eggs.
I quickly got used to heading out to the reefs from the beach in front of the lodge restaurant. My kit was carried aboard and the boat waited for me to finish my breakfast. It doesnt get much more civilised than that.
Several miles due south of Vamizi, Luis took me to the sunken island. As we dropped anchor on shallow sand-flats green with turtle grass, a tell-tale ripple told me there was a current. And a dark blue line on the surface waters told me there was a drop-off.
A backward roll took us into 7 or 8m of water but following Luis over the lip and onto the drop-off there was nothing but the wall and endless blue.
Facing the wall, I could see it stretching for hundreds of metres in both directions, an endless vista of shimmering life, comparable only to walls I have dived in Indonesia and Papua New Guinea. There are sponges, yellow, green, brown and black. Some grow like fingers sticking out from the wall, others creep across the limestone like spilled paint, and some are barrels, dark brown gourds big enough to hold a football.
Giant gorgonian fan corals sprout from the wall, their delicate skeletons as wide as I am tall. There are forests of them, ghostly shapes fading into the deep below me.
A starry puffer uses one gorgonian like a chaise-longue while a striped wrasse picks its gills clean of parasites.
Thirty-five metres down, a barrel-chested giant grouper with fat lips and bulging eyes comes up from the dark, 5ft long and weighing around 100kg. Looking up towards the shining surface of the sea, I spot groups of shy unicornfish, pointing their humped foreheads like bowsprits.
All too soon it is time to ascend, but I study the wall for the minute creatures that make diving so much more than a quest for close encounters with big fish. Within 10 minutes I have spotted three varieties of nudibranchs that I have never seen before, one of richest blue with purple marginal bands.
Twenty metres below the lip of the plateau, the limestone has eroded into overhanging ledges and small caverns where shoals of yellow-stripe snapper move together in a bright living chain.
On one shelf there are dozens of vivid anemone sacs, their stinging tentacles hosting pairs of clownfish from two different species. Such anemones, and I count 48 on one small patch of coral, can thrive only when the reefs do.
On the plateau we drifted in the current, while below me the healthy coral stretched on and on. All over the tropics, reefs are in terminal decline, prey to global warming, over-fishing and pollution from hotel sewage. Here, close to Vamizi, I was looking at a reef in all its raw natural beauty.

THIS UNDERSEA WALL IS ONE OF THE BEST DIVES IN THE WORLD. I didnt see any especially large pelagic fish during my visit, though Luis said he had seen sharks deep on the wall on other dives. But the diversity and condition of the reef made it seem unlikely that this was anything but a bio-system in rude good health.
The good news is that Vamizi has just completed its own airstrip, so divers can now take a shorter journey from London to Dar-es-Salaam, then fly in from the north rather than having to go through South Africa and Maputo to get to Pemba. But, hey, dont all go at once.


Divernet Divernet
Healthy
Healthy hard corals
dive
dive centre staff dont like to see you put yourself out
diving
diving is from the centres RIB
giant
giant clam
Three-spot
Three-spot humbugs, which live symbiotically with anemones
the
the lodge is a comfortable place to pass the time.

FACTFILE

GETTING THERE: British Airways flies to Dar-es-Salaam, and from Nairobi there are regional flights to and from Pemba.
DIVING & ACCOMMODATION: Vamizi Island Lodge (www.vamizi.com) has its own dive centre and an 8m dive boat accessing some 10 dive sites 10-15 minutes away. There are 10 en suite beach-houses.
WHEN TO GO: The climate is sub-equatorial, warmest months being October-April (30°C+), coldest June-August. Rainy season is January-March, when the water is warmest (26-28°C). From July-September it is 21-25°C.
MONEY:US dollars
PRICES: Rainbow Tours (020 7226 1004, www.rainbowtours.co.uk) can arrange an eight-day holiday to Vamizi from £2695 per person (based on two sharing). The price includes prepaid departure taxes and fuel surcharges; seven nights accommodation at Vamizi including all meals, local drinks and many activities; and transfers.