THIS IS SIMPLY THE BEST visibility I have ever seen! We are 6-8m deep in a chamber festooned with stalactites and stalagmites, and it is as though the place was bone dry. Our powerful HID lighting slices through the darkness, allowing us to trace the course of the thin white dive-line until it disappears way off in the distance.
This cave is known simply as Asphalt, because there used to be a road construction plant just outside it.
We had been told that it was good, but from the outset its clear that this is one of the best I have dived. It should be renamed in a manner more befitting its natural splendour.
We had been in the Dominican Republic for a week, and covered one hell of a lot of it. What an island of contrasts! It was proving to be not only a culture shock, but also a rich and varied area for diving.
It hardly seemed like seven days since we had arrived at Punta Cana airport at the extreme eastern end...
A small group of musicians is playing merengue and a butterfly wafts past my face as I descend the steps to the warm tarmac. The sky is clear, and as we walk in the sunshine I notice a swallow disappearing into the palapa-grass roof of the main terminal building.
There are pretty girls, in what I presume is national dress, quickly posing for pictures with the arriving holidaymakers as we approach the immigration desk. There is a real carnival atmosphere, not quite what I had expected.
We are assigned an interpreter and a driver, at our disposal for the week, the idea being that we sample some of the best diving at a variety of venues right across the Caribbean island.
First stop is Bayahibe, a bustling little tourist resort with a luxurious hotel called Dreams La Romana. The place is perfect for diving, but our dive host had broken down on the road, so our initial activities were jeopardised.
Hasty changes mean that we find ourselves in the hands of a superhero Russian dive guide, Olec.
He takes us to a magnificent set of caves a half-hour from the hotel. An eager, smiling porter carries the heavy tanks down into the cavernous hole in the ground and, a few minutes walk from the 4x4, we are at the waters edge.
Before us lies a small, placid lake sporting visibility of 50m or more in 24°C fresh water. A small party of holiday-makers arrives by horseback, and they swim and frolic off to one side as we get ready. Then we swoop down into the room-sized tunnel for our first adventure.
Within a few metres, it is apparent that there are underwater formations here to rival the best in Mexico, which are generally regarded as the best in the world.
I hit a problem. My remote flashgun wont fire, and the underwater photo shoot is instantly rendered a disaster.
Abandoning the camera on the tunnel floor, we settle for diving! Its big and crystal-clear, with a silt-free rocky floor, so just about anyone could dive the initial section of this cave, and theres plenty more on offer for those with some cave training.
Olec knows the place like the back of his hand, and we are impressed as he nimbly slides between narrow gaps into an area into which few novices would dare to venture. The tunnel meanders on and on between craggy walls of light-coloured limestone. Its a joy to dive.

PHOTOGRAPHIC PROBLEMS SOLVED, we move on to the extreme north of the island. Its one hell of a drive, on roads that require major investment, but it helps us to appreciate how big the island is, and how varied the landscape.
Kenny, our driver, sees himself as Lewis Hamilton. Nothing fazes him, and no one passes us. To us he is Mr Cool; previous visitors have dubbed him Kenny Ferrari.
Our interpreter, Carlos, is a star in every sense. He too is as calm as anyone Ive met - hes Mr Problem Solver. Helen (Rider) and I have the perfect support team.
At Sosua we are in the hands of Northern Coast Diving, run very efficiently by ex-Brits Marcos Santana and Colin Williamson.
Disappointingly, we have just missed the annual spectacular presented by the humpback whales that visit in numbers between January and March and, despite what it says in the Lonely Planet guide, I dont think youll get to see or dive with manatees here.
They are exceptionally elusive, even for those in the know.
The visibility in the ocean looks great, but were determined to check out those unusual spots that, sadly, are often dismissed. El Du-Du Caves at Carera are thoroughly recommended. This dive site is a large, sheltered inland lagoon set beneath low limestone cliffs. It may look like a flooded quarry, but its completely natural - a beautiful, peaceful spot, ideal for novices and technical divers alike.

AN EASY ENTRY DROPS into 10m of water, with visibility half as much again. To the left and right of the lagoon, huge dark tunnels lead off. Very heavy-duty guideline has been installed in the initial sections, which is reassuring and very easy to follow.
To the right from the entry point is a tunnel with stalactites leading through to daylight, and another enormous dry entrance just 50m or so distant.
Only in the very middle is the darkness complete; this is a superb cavern dive in less than 15m of water.
We make an extended 350m cave penetration, savouring a variety of underground passage, more flowstone decorations, haloclines and increasingly clearer water the further in we go.
Area three, Pedernales, lies in the extreme south-west of the island, near the border with Haiti.
As previously we have little information about this remote area. It is apparent that, as yet, it has little in the way of tourist infrastructure, and no diving facilities. We have come here on a 3/4-day mini-expedition, because this place is very special.
Pedernales has a quiet, relaxing atmosphere. Compared to the capital, Santo Domingo, or the north coast, this is tumbleweed country.
Next day we really are in the outback - wow! Outside the town, we wander through cactus jungle, surreal but impossible terrain to negotiate unless a path has been cleared by machete.
Piscina, a glorious natural swimming pool, is only a couple of hundred metres from the road. This fabulous dive site sports a variety of different-sized tunnels ongoing at depths beyond 40m, but it is Asphalt Cave that really excites us. Its only a few metres from the road, with the dive base about 30m underground.
Porters ensure that we get to the waters edge with next to no effort, and what unfolds is a spectacular that would encourage just about anyone to take up diving, just to share in the experience.
I am convinced that the water clarity here is better than that in Mexico, and the formations are magnificent.
We follow the main tunnel for hundreds of metres, through a wonderful variety of cave passages. Almost everywhere flowstone draperies provide endless photo-opportunities.
The depth has been a maximum of 11.5m as we rise to air near the end of the cave, so in just about every way this is a stress-free dive. We spend more than 75 minutes relishing every moment.

THE CAVES MAY BE SPECTACULAR, but why there is no dive centre at Pedernales I cant imagine! The beaches are among the best in the Caribbean, and offshore the diving must be good, even if it is undertaken from relatively small fishing boats.
We see the fishermen coming ashore with enormous crabs and lobsters; this place has real tourist potential!
In Santo Domingo we visit the Dominican Republics best-known wrecks, the Hickory and Limon, at La Caleta. Our dive-boat is rudimentary and our skipper a humble fisherman, but like everybody we have met, he cant do enough to make our day a special experience.
As we descend the shotline a fair current is running and the visibility, disappointingly, is much the same as the depth - 20m. Both wrecks are broken, but seem sound structurally.
The Hickory in particular offers good opportunities for a nose around the hold, and fortunately its not one of those places that will silt out badly.
We dont see any large fish in this area, though deep inside and flitting between the jumbled metalwork are shoals of small ones hiding in the darkness. Given the proximity of the wrecks, we move directly over to the Limon, stopping briefly to check out a very large circular structure midway between the two.
This is an old floating pontoon, apparently, but it makes for an interesting few minutes distraction. Its an easy swim over what otherwise looks a barren seabed, and we ascend from the Limon barely into decompression.
As we reach shore after the dive the whole community, it seems, piles into the water to drag and push the heavy boat back up the sandy beach. There are big plans afoot for this area. To stimulate the local economy, promote diving and help regenerate fish stocks, it is proposed to develop something of an underwater museum or park.
The Hickory, a 39m steel salvage ship, was a deliberate sinking in 1984 to encourage diving. But the new plans are altogether more futuristic, involving the installation of 10 or more impressively large structures ranging from depictions of manatees and other sea life to erstwhile native warriors, the Taina.
The development of the submarine park at La Caleta is a project overseen by the Foundation Vida Azul, which is waiting for the governments go-ahead.

IN THE SUBURBS OF THE CAPITAL, Santo Domingo, and of equal interest to us, lie a variety of caves that are very easy to access. El Roco is a memorable name, even more so when you discover that of an evening it serves as a disco.
Unquestionably the best site here is Taina - in fact, its one of the worlds best cavern- and cave-diving sites. With more than a kilometre of underwater passage, this is the longest cave on the island and so good that we dive it twice.
From the outset there are large flowstone formations, well within reach of recreational cavern-divers, and huge air chambers in which, from the moment your head breaks surface, the scene is breath-taking. The air quality is perfect, so you can take your regulator out and just take in the scene.
All around hang pristine stalactites and stalagmites of every hue. It may only be 50m or so from dive base, but youre transported to another world here.
A visit to this cave alone would make a divers visit to the Dominican Republic worthwhile.
In the hands of the tourist board, we were exceptionally lucky to get such a comprehensive overview of the island. Overseas visitors generally stay in resorts such as Dreams La Romana, but at places such as Pedernales we were always made to feel welcome at smaller hotels.
The island does need to upgrade its roads and tourist infrastructure, but it makes a wonderful holiday destination for divers. Given the chance to return, youd have to hold me back!