As a trainer, people often ask me: Where can we go to dive in caves
     Unfortunately, that many places I can recommend.
     For those coming fresh to the activity, it is clear that the UK has only limited opportunities for cavern-diving. The readily accessible sites can be listed on one hand.
     By and large, the training offered in the UK is sound, and if divers become confident in our cool and perhaps murky waters, they should later relish the delights of cavern-diving in other, more inviting, destinations. Which is what gave me the idea for a book which will be published next year as a companion volume to Diving in Darkness.
     Here we take a look at some of the places you can visit to get a taste of what cavern and cave-diving is all about. You can approach many of these sites with different levels of experience - at Billingshurst Caves in Gozo or the Emergence de Ressel in France, for example, you can explore just inside the entrances to begin with and later, with the appropriate training and suitable preparations, venture deeper inside.
     And many of these destinations have dive centres nearby that can offer underwater tours or training as needed. A good example is the island of Malta.
This is not a name readily associated with cavern-diving, but after a recent visit there, I would rate it highly.
     Situated in the middle of the Mediterranean, 60 miles south of Sicily and 100 miles north of Africa, it consists of three islands - Malta itself; Gozo, a half-hour ferry crossing from the main island; and the tiny Comino, which is sandwiched between the two bigger islands. All have caverns, and the visibility is exceptional.
     There are plenty of dive stores, everyone speaks English, and most of the diving is shore-based, which substantially increases the flexibility of activity. The most famous landmark - shown in all the tourist brochures - is the spectacular Azure Window, which lies on the western side of Gozo.
     This is also the site of the Blue Hole Cavern, a fine circular shaft very close to the foot of the window. To dive in the clear blue water of the entrance with sunlight streaming in from above will set a scene to last a lifetime. Viewed from the darker recesses of the cavern, the sculpting of the natural rock arches and the shafts of sunlight piercing the ethereal haze is nothing short of magical.
     You dont need specialist equipment, such as a line-reel, to explore and savour this site by day. The cavern or chamber stretches back only 25m at 15-20m depth, with that magnificent blue portal as a constant beacon. This is a very special dive-site!
     A short distance away, along the rugged underwater cliffs, other delights such as the Chimney will enrich any underwater tour from the Blue Hole.
     If conditions are perhaps too rough to access the Blue Hole, the Inland Sea just a few minutes drive away will provide an equally enjoyable all-weather alternative.
     Here one can access a narrow tunnel which leads through the imposing cliffs lining the north of the island to emerge upon stark, sheer walls at 25m depth.
     Remaining at a safe depth is imperative at all times. The water surface is well below the ceiling of the 40-50m tunnel but ascent to the surface must be considered very carefully and is generally not advisable. Here, the surge between narrow walls is frightening in any swell, while in calm conditions a multitude of small boats ply the waterway on sightseeing tours to and from the open sea.
     At depth, which varies between several metres in the Inland Sea to 30m at the northern exit, one is spared such hazards. There is always sufficient light for directional requirements, although a torch is regarded as a must.
     Taking careful heed of local advice, and when conditions permit, one of the best dives on Gozo is Billingshurst Cave. This lies on the north coast a mile or so west of Marsalforn.
     As you stand on the intriguing man-made salt pans, which date back to Roman times, directly above the cave, there is nothing to indicate the spectacular nature of the enormous tunnel below your feet. The stride entry is committing; once youre in, youre in!
     The swell sloshes noisily into undercuts and exit here is nigh on impossible. Everyone needs to be clear as to the direction and nature of the exit point, which lies more than 100m away.
     As you descend, a grey void immediately appears beneath the land. The ceiling of this wide tunnel stretches back at 15m depth, but the bottom lies at 30m.
     At the floor, a succession of pebble ridges running from wall to wall conveys the clear impression that this rugged coast is not always so calm.
     Eventually, perhaps 40 or 50m back, the pebbles give way to finer silts, and by now ones eyes are more accustomed to the lower light levels.
     This is an awesome void. The tunnel is perhaps 25m wide and certainly more than 10m high. By now it looks a long way back to the entrance, especially if you have only a single cylinder. Divers have perished here, so it is prudent to curtail any further penetration, unless the dive has been planned very carefully.
     Ahead, massive boulders rear up in the darkness and good lighting is essential. This is a place where the reassurance of a line is appreciated, and one has been installed on the left side.
     The vast tunnel rises to air in a huge chamber 100m in. Surprisingly, this marks the conclusion of the cave. The darkness may appear oppressive, but if torches are turned off for a moment, the dim light of the surface world is just about visible.
     It feels like a long way home from here, especially when one considers that it may take 15 or even 20 minutes to swim from the entrance to the point where one will exit the water. A 15 litre cylinder should be considered as a minimum for this superb dive.
     Any number of challenging dives can be found dotted around the three islands, but if time is short and you wish to tour somewhere very special, but less committing than Billingshurst, take a boat to Comino Caves.
     These lie on the north coast of Comino, some half hours journey from either of the two larger islands. The caves here are situated in less than 15m of water and the principal swim-through is magnificent. This is holiday diving at its best. If youre lucky, you can also have a swim in the famous Blue Lagoon on your way home.
CONTACT St Andrews Divers Cove, 00356 2155 1301, www.gozodive.com

UK & Ireland
Caves such as Porth yr Ogof in the Brecon Beacons are weather-dependent, with water temperatures ranging from 5ÂC in winter to 14ÂC in summer.
     This site provides an ideal taster venue for those of limited experience (much longer cave dives are possible here, but these are suitable only for experienced side-mount divers who are happy in low visibility).
     Mines, such as the old slate workings at Hodge Close in Cumbria, give that extra dimension to UK diving. These are superb in the right conditions.
     But if one had to pick just one venue in this temperate part of the world, it would have to be scenic Doolin on the west coast of Co Clare in Ireland.
     This submarine complex has it all, including profuse marine life, all in clear spacious tunnels. But to dive the Green Holes of Doolin entails the risk of acute frustration because of the sea conditions.
CONTACT Martyn Farr, 01873 811085, email: Martyn@farrworld.co.uk

By ferry and normal four-wheeled transport, the site within easiest reach is the department of Lot in southern France. Predictably, summer and autumn are the recommended times for diving its subterranean waterways.
     Given that this area is inland, conditions are reasonably assured, with water at about 13ÂC for most of the year.
     This is probably the most popular area for cavern and cave-diving in Europe, with any number of sites such as the famous Emergence du Ressel, Trou Madam, St George and Font del Truffe.
     CONTACT Andrà Grimal, Gramat, 0033 05653 87536, www.plongee-quercy.com

Canary Islands
In bleak midwinter we all appreciate a little sunshine, and the Canary Islands is well worth considering for a short break. Lying off the north-west coast of Africa, it has everything to commend it to divers of all levels.
     Its a 4.5 hour flight from the UK to the Canaries, and perhaps the best island to head for is Lanzarote. Youre in the same time zone, so dont claim jet lag!
     There are good package deals, and the place offers value for money. In December air temperatures are around 20ÂC, while that all-important water temperature is a balmy 18ÂC.
     Here you can explore lava tubes - natural cavities formed thousands of years ago when molten lava flowed from now-dormant volcanoes. The longest submarine tube in the world lies here: the Atlantida Tunnel, 1600m long.
     Dive from Playa del Carmen to the aptly named Cathedral Cavern at 30m depth, then finish off at a mere 5m depth in the 30-40m-long tunnel beneath the quay itself.
CONTACT Deco Stop Dive Centre, Costa Teguise, Lanzarote, 0034 928 346248, www.deco-stop.com

Mainland Spain
The Mediterranean coast of Spain has some spectacular offshore cavern sites accessed by boat from LEstartit in the Costa Brava. The flight from the UK to Perpignan takes less than two hours, but Girona is also a good choice as it is nearer to LEstartit.
     A number of interesting swim-throughs lie directly adjacent to the mainland to the north, but perhaps the best diving lies a mile offshore at the Medas Islands. There is a 100m swim-through at the Dolphin Tunnel and a shorter swim at Cueva de la Vaca Tunnel.
     The Costa Brava, as the translation implies, is highly dependent on sea conditions and at certain times of year, in winter in particular, visibility can be atrocious. The Costa Blanca, which is rather less challenging, has one gem of a site at Cala Moraig, just south of the principal town, Javea.
CONTACT Unisub LEstartit, www.unisub.es

Balearic Islands
Mallorca and Menorca are always popular. Both present superb cavern-diving, though only the former contains any lengthy cave networks. Diving is at its best between March and October.
     Most of the cavern diving in the Balearics is undertaken by boat, but the longer cave sites of Mallorca are all land-based. The ideal base here is perhaps Puerto Pollensa. The principal operators on both islands are multilingual, and used to running this type of dive.
CONTACT SAlgar Diving, Menorca. 0034 971 150601, www.salgardiving.com
The island of Sardinia is a relatively little-known destination for British divers, but one with huge potential. There are spectacularly large undersea caverns in the north-west, but perhaps the single most interesting area lies on the east coast, south of Cala Gonone.
     There are a number of clearwater caverns and some extremely impressive freshwater risings here.
     The latter present much longer caves - with associated thermoclines and haloclines - and a lot more besides! Its a fabulous area, but comprehension of English is variable.
CONTACT Location Sardinia 0039 329069 4063, www.locationsardinia.com

Cavern-diving from a spacious gulet in places such as Fethiye or Olu Deniz in Turkey can be an idyllic experience. May to September is the main season.
     Its a 3.5 hour flight to Dalaman, with a two-hour difference in time. Water temperature is still 24ÂC late in October.
CONTACT European Diving Centre, 0090 25261 49771, www.europeandiving.com.tr

The start of a dive in France's Emergence de Ressel system, which provides a range of experiences for divers of different ability levels
Mines frequently present clear water at times when caves are inaccessible or flooded. Places such as Hodge Close slate mine, in Cumbria, are among the finest underground dive sites in the UK.
Spectacular entrance to Gozo's Blue Hole
Pollensa Bay in northern Mallorca has a number of caverns in sheltered offshore locations
Situated between Oludeniz and Fethiye, in Mediterranean Turkey, it is a lengthy boat ride to reach Coral Cave, but with a good guide the dive will be a real adventure.
Beginners courses
Cavern courses are intended to raise your environmental awareness without subjecting you to the many additional concerns, and real hazards, experienced in deeper caves.
     Recreational divers must understand the clear distinction between cavern-diving (in which your exit point is usually visible) and diving in the deeper cave zone.
     As a cavern-diver you can use your normal equipment, with which you are familiar and confident, although the configuration may be modified slightly for safetys sake.
     This type of diving does require awareness and respect for the environment and this follows naturally from having the right attitude, training and experience.
     The course should provide a structured, well-supervised introduction to diving in overhead environments, and there are a number of new skills to be taught and practised.
     Cavern-diver certification is an internationally recognised qualification and divers with this card will be allowed access to similar sites worldwide; it is the first important step in a series of programmes leading to full cave certification.