TASMANIA'S REEFS, situated near the edge of the continental slope, are celebrated for giant kelp forests that can tower up to 30m towards the surface.
 But Tassie is also home to rich and colourful invertebrate life, amazing sponge gardens, spectacular cave systems and more than 480 shipwrecks (not all accessible, of course). It also boasts marine species found nowhere else in the world.
I had lived in Australia for five years, so why had it taken me so long to dive in Tasmania I finally made the two-hour flight to Australias southernmost state, and my first stop was on its south-eastern peninsula.
 Eaglehawk Neck is said to offer some of Tasmanias best diving, and boasts spectacular underwater caves. One of the most dived is Cathedral, a series of interconnected honeycomb caves running alongside the cliff face of Waterfall Bay. I joined Mick Baron from Eaglehawk Dive Centre one wintry morning on a 20-minute boat ride out past some of Australias largest sea cliffs, towering 277m above the sea.
 These walls drop way below the waterline, creating a home for a rich variety of marine life. A couple of Australian fur seals play in our wash as we cruise by and Mick tells me that dolphins and whales are often seen here.

Slap in the face
Cathedral Cave is an exciting prospect for divers of all qualification levels. Maximum depth is 21m outside the cave and 18m within but the tunnels lead back quite a way, with narrow offshoots branching in all directions. Mick and fellow dive-centre owner Gary Bell have spent hundreds of hours exploring and mapping the caves, but admit that there are still areas that remain a mystery even to them.
 As I don my semi-dry, Mick informs me that the water is a cool 14.5C. This is when I start wondering what on Earth made me leave my drysuit at home, and the thought stays with me as I plunge in. I feel as if a wobbegong shark has just slapped me across the face with its tail, its that cold.
 A penguin, popping its head out of the water to check the commotion, watches as we descend to the cave entrance.
 As we pass through, light penetrates into the various passageways, creating an ethereal mood. I feel dwarfed by this magnificent structure. Below me I note a rich array of fish life - southern gobbleguts, rough bullseyes, goatfish, old wives, magpie perch, blue-throat wrasse and banded morwong.
 We venture deeper into the gloom, and as we round a corner, an unforgettable scene unfolds. We have entered the Skull Cave.
 I would have been lost for words if I could talk under water. Skull Cave is a meeting point of several large arches that exit to the ocean. Light streams in through these arches, making them look like giant eye sockets.
 As we pass the arches, a school of bullseyes dash out and lead us to the Altar, a passageway with a large flat rock at the end of it. Shafts of light illuminate the rock, like something from an Indiana Jones movie.
 We glide over the Altar and into a smaller cave that will accommodate only one diver at a time. Mick turns to check that Im OK to go on, and my adrenalin is rushing as we dive deeper into the underwater passageway.
 This is Revelation Bend, and for a few minutes we duck and dive through this intricate little system, home to curious crayfish and boarfish.
 After about five minutes, blue arches appear and we exit back into Skull Cave. Its an overcast day, but the shadows and silhouettes around the cave walls are still spectacular. This dive is every wide-angle photographers dream.
 Amazingly, its every macro photographers dream, too. A multitude of invertebrates, sponges and fish normally found at deeper depths hide on the Cathedrals ledges. Yellow zoanthids and pink jewel anemones share wallspace with sea-spiders and sea-stars. I start counting spiny rock lobsters and crayfish but get bored when I reach over 30. Thats when I start looking for another fish endemic to south-eastern Tasmania - the rare handfish.
 That morning, Mick had said: If youre really lucky you might find a Ziebells handfish hiding on the ledges. It looks like an anglerfish but without the warts and spines. It has smooth skin and comes in bright colours like pink and red. Its also thought to be poisonous.
 The red handfish had not been seen for 100 years until abalone divers discovered one in the 1980s near Port Arthur, about 10 miles away. Mick says he sometimes finds them in the cave at about 10m - but unfortunately this is not to be a handfish day.
 Finning back out, I spot a cute Shaws cowfish lurking shyly between two rocks. My torch blinds it momentarily and I watch it spin in circles before it is chased away by a skittish morwong.
 On the ascent we spare a few moments to search for weedy sea dragons, often seen floating in rocky kelp patches beneath the boat. But all we find today are gurnards, kelpies, leatherjackets and a sleeping marbled sting ray.
 Tasmania is not known for big schools of fish at this time of year, but the previous day Mick had seen the biggest ball of redbait he had ever seen swirling outside the cave entrance. As so often, I should have been there earlier.
 But as I surface holding out my camera, toes and fingers numb with cold, I wear that big stupid grin that is involuntary after a great dive.
 And, a cup of hot soup and a choccie bar later, we head round the corner to the sheltered Waterfall Bay in search of a weedy sea dragon. Needless to say, Mick finds me one.
 Other attractions in this part of Tasmania include the emerald giant kelp forest in Fortescue Bay, a 40-minute boat ride from Eaglehawk Neck.
 When the kelp is in full bloom, this is the sort of easy shore dive that everyone can enjoy. The kelp rises to the surface from a sandy and rocky bottom at around 10m. This is a promised land of colourful sponges and, if youre lucky, weedy sea dragons. Look in crevices for crayfish and abalone, too.
 Australian fur seals are found at Hippolyte Rock and Cape Pillar, and for experienced wreck enthusiasts, Eaglehawk Dive Centre offers trips to ss Nord, a steamship that sank off the Neck in 1915. Its in 40m and can be subject to strong currents and poor visibility.
 But I was heading for the enchanting town of Bicheno (Bish-en-o), north-east of Tasmanias capital Hobart. Its a popular tourist destination in summer, but the best time for divers to explore its underwater realm is in winter.
 The cold water brings 30m-plus visibility, and with so much to see, an extra few metres of viz is a must.

Golden glow
Aboard Bicheno Dive Centres Devil Cat Iruka, with Pat Taylor as my guide, we head for Governor Island Marine Nature Preserve and one of the parks popular first dives, the Canyon.
 Its deep, colourful and has a stunning sponge garden. You drop directly into the canyon at between 30 and 38m, checking out on the way down a 5m reef wall thats chock-a-block with yellow zoanthids. These yellow daisies give off an ethereal golden glow - its a beautiful sight and soon becomes a familiar one in Tasmania.
 We reach a gully boasting a kaleidoscope of sponges, sea-whips and ruby rich finger sponges. Shine a torch on any of these creatures and their colours jump out at you - they look good enough to eat.

Lobster harem
This is the realm of the basketstar, with many different shapes and sizes clinging to sponge hosts and sea-fans.
 The occasional butterfly perch, morwong and trumpeter float by, and there are some unusually big boarfish. As we cruise round, we are tracked by a huge, inquisitive green wrasse.
 I hear a strange squeaking sound. My buddy is trying to attract my attention. I dash over and soon forget about my impending frostbite.
 Poking out from a large crevice is the biggest rock lobster I have ever seen. Its head alone is at least three hand-spans wide, and its surrounded by a harem of smaller lobsters, crammed in as tight as biscuits in a packet.
 This is crayfish country, too, and again the number of unusually large ones demonstrates how life can flourish under the protection of a marine reserve.
 Ascending the hairy wall, we cram in as much critter-spotting as we can, including a yellow sea-spider hiding at the base of a sea-whip.
 Our safety-stop point is Mount Everest, where the top of the reef comes to within 5m of the surface. Theres a fair bit of surge today, and as I watch the kelp sway, I feel a touch of nausea coming on.
 The kelp is getting to me. But theres plenty more of it on our second dive at Canuck, a site that apparently got its name following a visit from a Canadian military band!
 The dive starts with a drop to the opening of a small swim-through. Pink jewel anemones sparkle and yellow zoanthids carpet the walls. We move along the side of the reef looking for nudibranchs and picnogonids, and as we descend to the 20m area, a pretty sponge garden greets us.
 We turn and head towards a large boulder to check out even more sponges and anemones. Finally we head back up the kelpy gully to look for large pumpkin sponges. Again, crevices, ledges and holes are packed tight with rock lobsters.
 A friendly long-nosed boarfish swims by to give us the once-over before darting off through the kelp. The stuff seems to be everywhere, and it envelops you on every safety stop. In fact it is less plentiful than it seems (see below).
 All Bicheno Dive Centres guided dives are from its boat, but there are plenty of shore dives for the more independent diver, among them the Rock at Breakwater.
 This bommie stands tall on the sand in the middle of a bay. Being about 100m from the entry point, its a bit of a swim, but its worth it, as you are pretty much guaranteed to see charismatic weedy sea dragons lurking in the kelp on the way.
 Circumnavigating the rock takes only a few minutes, so we take our time, checking out the gurnards in the sand, marbled sting rays swimming gracefully through the kelp and schools of bastard trumpeters. The latter name, I am told, derives from the fact that this fishs brother, the stripy trumpeter, is much tastier, so this a fishermens response on snagging the wrong trumpeter!
 On the way back we have time to check out the shallow reef that descends from the shoreline. Orange floating anemones waft in the surge and a school of morwong forage in the sandy patches. The reef is fairly barren, and the closer to the boat ramp, the kelpier it becomes.
 Youll be lucky to get 15m depth on the Rock and its hard to get lost if you go round it and back again, so its great for beginners. Just dont surface in the bay itself, as boat traffic can be heavy.
Too many visitors, including Aussies, overlook Tasmania, heading instead for the Great Barrier Reef in Queensland or Ningaloo Reef in Western Australia. Dont miss out if you get the chance to explore this wildly enchanting land of rugged coastlines, breathtaking scenery and unique underwater bio-diversity.

A view of Eaglehawk Neck, with its dramatic cliffs
A weedy sea dragon at Waterfall Bay.
Starfish at Bicheno
Fields of bright yellow zoanthids like these at the Cathedral give off a golden glow and are a characteristic underwater sight in Tasmania


GETTING THERE: Fly to Tasmania from the UK with Qantas via Singapore and Melbourne. Eaglehawk Dive Centre will pick up divers from Hobart Airport, or hire cars are available at reasonable rates. Eaglehawk Neck is a 45-minute drive. Flights from the mainland to Launceston are often much cheaper but its a 3.5 hour drive. Bicheno is a two-hour drive from either airport.
DIVING: Eaglehawk Dive Centre, 00613 6250 3566, www.eaglehawkdive.com. au. Bicheno Dive Centre, 00613 6375 1138, www.bichenodive.com.aum.au
ACCOMMODATION: Both dive centres offer on-site backpacker-style accommodation for $25-40 a night with shared kitchen and bathrooms, or you can opt for more luxurious hotels, motels or B&Bs.
WHEN TO GO: June to September, though winter is a good time for diving with seals. Air temperatures range from 15-21°C, while water temperature in summer is 15-18°C and in winter around 12°C. 7mm wetsuits or drysuits are recommended.
CURRENCY: Australian dollar
COSTS: Return flights cost around£900. Boat dives cost around£16 per dive..at $35 each.
FURTHER INFORMATION: www.discovertasmania.com

Giant kelp in trouble
Forests of giant kelp (Macrocystis pyrifera) are to the ocean what rainforests are to land. They represent areas of high biodiversity and are vital habitats for many marine creatures, such as rock lobsters and abalone.
  Like giant trees suspended under water, these large, canopy-forming plants grow in dense beds along the reefs of South Australia, Victoria and Tasmania. Or, at least, they used to.
  The waters around Tasmania once contained the largest area of kelp forests in Australia, but two-thirds of them have disappeared in the past 50 years, with more than 90% lost in some places, according to a report by marine ecologist Dr Karen Edyvane commissioned by Environment Australia (www.dpiwe.tas.gov.au).
  Global warming is killing the kelp. In the past half-century sea temperatures on Tasmanias east coast have risen by as much as 2C. Kelp cannot survive or reproduce in waters above 18C.
  Ten years ago, Bicheno boasted healthy giant kelp forests, but slowly the warm Australian Eastern Current (best known for its performance in Finding Nemo) now flows warmer and more nutrient-rich, so its kelp forests have all but disappeared.
  The black sea urchin (Centrostephanus rodgersii) is also doing its bit. As El Ni–o kicks in, urchins that normally feed on algae go wild and graze kelp instead. The experts are talking extinction - and even the government is listening! But recent years have seen little action, and too little research carried out, with surveys limited to the east coast.
  Kelp Watch is a community-based research and monitoring project dedicated to assessing distribution and health of the forests, and is part of the Tasmanian Giant Kelp Project. It collates information from fishermen, divers and the public, and is designing a monitoring and recovery program.
  This is based on lessons learnt from Californias large-scale losses in the 1940s, where, over 30 years, urchin control programmes, commercial urchin fishing, kelp restoration efforts and sewage disposal improvements all helped to save the giant kelp. Visit www.coastview.com.au/diving/diveindex.htm or www.kelpwatch.tas.gov.au.

With the giant kelp forests under threat, Tasmania hopes to learn from Californias experiences in the mid-20th century