IMAGINE DIVING THE LUNAR SEA OF TRANQUILLITY. Dark monochrome sand and islands of jagged grey rocks rise steeply from the depths. Fill it with some of the clearest water in which you have ever dived, and add a sprinkling of fish.
 Its what Im daydreaming about while diving at La Palometa, Roques de Anaga, off the northern tip of Tenerife.
 The water is so incredibly clear that I can almost see the entire dive without having to swim anywhere. I could be gliding about in a spacesuit rather than diving in the Atlantic.
 The grey volcanic basalt has cooled into a jigsaw puzzle of upright crystalline columns, a bit like the Giants Causeway off Northern Ireland, or Fingals Cave off Mull, but built on a much larger scale.
 Closer to the rock, the lunar impression breaks down. The rocks have a fine and almost invisible coating of short, hairy hydroids, creating a light flock wallpaper patterned by a stampede of grazing spiny sea-urchins.
 We swoop down a canyon to see fronds of black coral growing beneath a slight overhang. The light and my eyes tell me that the depth is about 15m. My dive computer is more accurate - it says 40m. Broken columns of rock fractured from the face are tumbled like a game of jackstraws below.

We continue around the pinnacle in an anti-clockwise direction. The deep slope becomes gentler and I rise to a comparatively shallow 18m, staying with the steeper wall, now adorned with patches of bottle-green sponge. Shoals of biscuit-coloured damselfish fill the margin about the rocks. Juan Carlos Spanish fish ID card names them as fula blanca.
 I am buffeted by waves breaking above. It isnt that the sea is rough - in fact its almost flat - but the Atlantic groundswell pushes up and down several metres as it hits the reef. In the clear water it feels as if I am too shallow, and I have to check my computer to reassure myself that I am not about to break the surface.
 The fine weather and calm sea is holding, so next day Juan Carlos takes us on an even longer boat ride - we travel for more than one and a half hours by RIB, past Roques de Anaga and on to a submerged reef.
 Looking over the side of the RIB, I can see that the water is an intensely deep blue. Its the sort of blue that suggests great clarity and great depth.
 As we cross the reef, the echo-sounder is hardly needed. A casual glance over the side shows the grey basalt below.

If I were driving a boat and could see the seabed I would be worried about grounding. I suppose I have been conditioned to it. Here I peer over Jean Carlos shoulder and see that the shallowest echo is actually 10m below.
 We descend into a house-sized tunnel, straight down into the top of the reef. The name of the site, La Catedral de las Nieves, gives it away. Even I can translate the beginning of that bit of Spanish.
 I can see the bottom of the cave below me. Ahead, it widens into a huge hyperbolic arch to the open sea. As I descend, I turn on my back to take photographs looking up at other divers entering the cave. I drift downwards until my cylinder makes a gentle clunk on the rock.
 Once again the clear water disguises the scale of the scenery. The depth is 45m and I can just see the boat silhouetted above a corner of the entrance.

The translation of the remaining part of the name intrigues me. Here I confess that my Spanish extends only to dos cerveza and a few clichés picked up from watching westerns and action movies. Things like Hasta la vista, baby. Back home I will use a web translation package to translate the whole thing to Cathedral of the Snows.
 Outside the cave, we loop out over an equally huge boulder field, before turning clockwise along the reef wall.
 A green and brown spotted moray eel rests on a ledge, surprisingly well camouflaged against the grey rock. The fish ID card says morena .
 Shoals of hundreds of tiny yellow wrasse mark the leading edge of the reef, groups of 30 or more dancing up to release clouds of spawn into the current. I complete the second half of my circuit of the reef above the edge at about 12m. Even then I am well into decompression before making it back to the shotline.

For a second dive we move a mile inshore to a similar basalt monolith. Flat-topped at 12m, with vertical sides and a jigsaw of hexagonal columns rising from 30m, the whole system lies along the line of an ancient lava flow.
 Off the reef, we encounter a ball of jacks. The ID card says jurel. I cant get close enough for my camera strobes to make a difference. There is plenty of natural light, so I take a few shots anyway. The resulting slide shows the fish in an overall context of grey-blue monochrome.
  Decompressing at 3m on the shotline, I can see a tiny blob moving across the rocks below. I am torn between completing a sensible stop and descending to 12m for a closer look. Common sense prevails and I identify the blob from a distance when the small octopus reaches out with a pair of tentacles to fondle the chain.

Perhaps I should explain my efforts to become familiar with local names for the fish. Earlier in the week I had become involved in a comedy of translation. I had asked Juan Carlos about sting rays and where we would find some. While we agreed on the rest of the conversation, somehow sting ray did not translate literally between English and Spanish.
 I resorted to signs and gestures, in a peculiar multi-lingual game of charades. I flapped my arms and got manta. I shortened my arms and flapped again: tortuga. I already knew that tortuga was Spanish for turtle. As in any game of charades, eventually all the clues click and the answer suddenly became obvious: chucho.

Back at the shop Juan Carlos gives me a fish ID card with names in Spanish and Latin. I am beginning to understand why scientists insist on Latin names for everything.
 I spot my first chucho of the trip on another dive at the Roques de Anaga. This time it is on the Roque de Fuera, a vertical-sided knife of basalt that rises a good 50m straight out of the sea. We are swimming along the wall at 20m when I spot it, on a patch of sand below.
 I spiral to 35m and approach commando-style, just negatively buoyant and crawling on my elbows. The chucho digs in to hide. My first shot spooks it; it circles and digs in again. I manage a couple more before it flutters off across the sand and fades into the blue distance.
 Just north of Santa Cruz, capital of the Canary Islands, the remains of the steamer Westburn lie in 30m, victim of an unusual sequence of events in World War One.
 The story begins with the German auxiliary cruiser Moewes raiding foray across the Atlantic. Over the first two months of 1916, the Moewe captured or sank 15 merchant steamers, a total tonnage of 57,835. Some ships were sunk, others returned to Germany under prize crews.

Such was the success of the Moewe that there were soon too many prisoners on board for the supplies available. Extending the Moewes raiding foray was considered more important than continuing to hold the captured crews, so the Westburn was used to land 200 merchant seamen in Tenerife, neutral Spanish territory.
 Prisoners ashore, on 24 February, 1916 the Westburn raised anchor for the last time. Waiting at sea was the British armoured cruiser Sutlej. Rather than risk losing the prize ship to the British, the Westburn was scuttled with explosives.

The visibility is once again spectacularly clear. Descending the shotline, I can pick out the general shape of the wreck almost as soon as I am below the surface.
 The wreck lies on an even keel, but is mostly broken down to the seabed. Engine, boilers and all machinery have obviously been salvaged.
 My first inclination is to settle in to take pics of the many and diverse fish that inhabit the wreckage, but Juan Carlos urges me on towards the bows. I soon realise what all the fuss is about. Huge dense shoals of fish cover the forward quarter of the wreck. The faithful fish ID card identifies them as salema, which I later identify as saupe, and sargo, which I could already recognise as some kind of bream.
 A smaller and more spread-out shoal of yellow-tail snappers cruise in and out, the dense shoals of saupe and bream parting to let them through. Higher up the food chain, a shoal of large jacks forces a bigger partition through the wall of fish.
 While thinking of the food chain, before diving we had spotted a great hammerhead cruising with its dorsal fin just breaking the surface, a classic Hollywood shark scene, but there was no sign of sharks on the wreck.
 On my third dive on the Westburn, I get back to studying some of the individual inhabitants. Dive one had been taken up with the big shoals of fish and dive two with the overall structure of the wreck.
 Among scatterings of anthias I soon find salmonete de roca (red mullet), lagarto (lizardfish), cangrejo arana (arrow crabs), moma (something in the blenny family) and pejeverde (a bright green wrasse, and most likely a male).
 Back home, I find myself pawing through both tropical and European marine-life guide books to find English common names, in some cases successfully, but often leaving me with the name from the Spanish ID-card and a general family name in English.

La Catedral de las Nieves had been an amazing experience, but from a photographers point of view the scale was just too big. A mile or so north of the Westburn, the caves at La Cueva Del Roquete are built on a smaller and more manageable scale.
 From the RIB I can see a grey seam of lava in the mostly red rocks of the cliffs rising hundreds of metres above.
 Below water this has cooled and solidified into a reef of billowing pillow lava that splurges across the sand, leaving deep undercuts, caves and arches. They dont have the awe-inspiring majesty of La Catedral de las Nieves, but are much more photographer-friendly.
 Not all the boat rides are long. When the sea gets a bit rough, or just for convenient third dives of the day, there are some nice local reefs within just a few minutes RIB ride from Radazul, the closest being on the outside of the harbour wall.

Most of the reefs run perpendicular to the shore. Formed by lava flows that have poured down the hillside and out below the sea, they have sometimes crystallising into vertical jigsaw puzzles of basalt columns, at other times they have softer outlines of pillow lava.
 Starting at the shoreline, these reefs are popular for training dives, but often flow down the dark sandy slope to 40m or more, providing dive sites to keep more experienced divers interested.
 On the way down just such a reef I spot a small octopus hiding in a crack. I make a mental note of the location before following the group down the reef to find a selection of moray eels on a wall at 35m.
Like the Mediterranean, Tenerife has both conger and moray eels, though I never spotted both sharing a hole.

On the way back to the shallows I lag behind and wait by the octopus crack. With the other divers out of the way, he soon becomes tolerant of me lurking with camera at the ready, and poses nicely between the rocks.
 Ashore, I settle down with the other divers for lunch at a harbourside caf. Some speak English with various levels of expertise. Under water there had been no language barrier. Over lunch most of the conversation is in Spanish, but funnily enough I find that with a few words of translation I can follow what is being said.
 There is a discussion of PADI versus CMAS training schemes, talk about our dives and what they had caught on video and digital cameras, and generally lots of joking and laughing.
 I point across to the third sardine from the left on Juan Carlos plate: I know that one, I took his photograph yesterday, I say. Diving and smiles are our common language.

Juan Carlos at the helm of the RIB, heading north
a sting ray, or chucho
a huge shoal of saupe above the bow of the Westburn
the photogenic octopus
Moray eel; video action on the Westburn
clear water and a jigsaw landscape of basalt columns at la Palometa
damselfish on the same wreck


GETTING THEREFlights with Monarch from Luton to Tenerife. Radazul is a 30-40 minute drive north from the airport.
DIVING:Juan Carlos Garcia Fernandezs Travel Sub dive centre is based in the marina at Radazul. The dive centre is fully equipped with rental equipment, including 12 and 15 litre steel cylinders, many with twin Y-pillar valves. For technical diving Travel Sub has nitrox, Draeger Dolphin and Ray rebreathers, and will soon have Inspiration closed-circuit rebreathers available, 0034 922 682423, e-mail: sd17116@autovia.com
ACCOMMODATION:Travel Sub can arrange packages inclusive of typical tourist hotel accommodation.
COST: A one-week package including flights, transfers, hotel, half-board meals and four days diving costs£315.
FOR NON DIVERS: The usual resort hotel facilities, entertainment and excursions.
BEST TIME TO GO: Tenerife has a pleasant climate year round.
DIVING SUITABLE FOR:The reefs and pinnacles off the north coast are definitely advanced dives. The inshore reefs are pleasant dives and suitable for beginners, especially with the characteristic good visibility.
FURTHER INFORMATION: The Travel Sub web site at www.divetravelsub.com is mostly in Spanish, with some pages translated to English.