Anglesey has an image problem. Poor viz, apparently, is the cause. A hurricane which wrecked the village of Towyn in 1990 was the culprit, as a result of which many divers have stayed away from this little island off the ast of north Wales in recent years.
But BSAC National Instructor Martin Sampson, who runs Anglesey Diver Training College on Holy Island, on the extreme north-west tip of Anglesey, feels it is time for divers to readjust their feelings about this part of the Irish Sea. There was a deterioration in the viz a few years ago, particularly after the hurricane in 1990, but last year we averaged around 6m, and the best was 15m. Between June and August it was consistently good.
I took up the offer to spend a long weekend on Holy Island, sandwiching three dives between an oxygen administration course. The viz never once dropped below 6m.
For such a small area, Holy Island seems to have a lot to offer divers. There are fascinating shore dives and several shallow wreck sites within a mile of shore for those just embarking on their sea diving careers. Experienced divers wanting more of a challenge can try the deeper wrecks further offshore.
Stephen Knight, a regular visitor from South Gloucester BSAC, confirmed my impression. There is a lot of variety - shore dives, wreck dives, something for novices and experienced divers.
There is also plenty of sea life. You can encounter seals at Rhoscolyn and North Stack and basking sharks can be spotted off Porthdafarch - although these are only likely to be seen in June. We had quite a few lobsters last year and there was an explosion of crabs and octopus, said Martin Sampson.
Porthdafarch Bay was the first dive of my stay. It is a small cove, bordered on either side by high, rugged cliffs, and an ideal spot for novices to train and do their early open-water dives. Entry and exit are easy - you just walk down or up the beach. The depths are shallow, about 8m maximum, but there are plenty of rock crevices to explore. Kelp covers the rocks, while the centre of the bay is covered in sand.
Navigation is also easy: you just follow the natural features, but a thick telephone cable runs down the length of the bay. It is a useful feature if you become disorientated.
Experienced divers can swim further out of the bay and explore a series of deeper gullies running up to the cliff face. Large shoals of pollack are often found gathered at the seaward end of the bay. During the summer months you could expect to come across bass and sand eels.
If you drained all the water from Trearddur Bay you would be left with scenery similar to the Nevada desert - flat stretches of sand interspaced with reefs erupting from the sea bed.
This is a good venue for dives close to the shore, although you will probably need to launch your boat from the slip to reach safer spots on the bays outside edges.
The central areas are to be avoided and an SMB is essential because there can be plenty of boat traffic. The dive site is sheltered and the maximum depth is, again, around 8m. There are no currents and this is a good area either for novices or experienced divers looking for an easy second dive of the day. Viz is usually good, occasionally over 10m.
Holyhead Harbour has two shore dives: Newry beach and Mackenzie Pier. Both are shallow dives. Newry beach is stony, with depths of 9m. This is the area you should aim for; further out the bottom is muddy.
Mackenzie Pier lies on the right side of the harbour as you look out to sea. It is a small pier with two sets of steps on the inner and outer edges, allowing you to dive around the structure.
With depths dropping to 6m, this is a good dive for novices, but it also makes an interesting night dive - as I discovered. The sea floor is covered by kelp but there is plenty of marine life on the pier wall. Divers should make sure their buoyancy control is good and select a course that does not double back on itself. The sea bed is soft, and disturbed silt will affect the return leg of the dive.
There are plenty of wrecks around Anglesey, due to the areas treacherous rocks and two wars worth of U-boat campaigns. Around half a dozen are shallow and within easy striking distance of Holy Island - perfect for divers in the early stages of their training.
Half a mile off Porthdafarch lies the wreck of the Missouri, which sank in 1886. She was a three-masted steamship that went down while sailing from Boston to Liverpool carrying 400 cattle. The wreck was rediscovered lying at 14m in 1963. The maximum current is about half a knot, so it can be dived at almost any state of the tide. Although now substantially broken up, the bows remain 8ft proud of the sea bed and you will be able to see bollards, boilers and decking. Big steel mast roots sometimes hold large congers. Martin Sampson and I encountered a shoal of pollack, starfish, ballan wrasse and sea scorpions - all in viz of about 7m. Other easily accessible wrecks, at depths of between 12m and 18m, are Hermine, Havso, Primrose Hill and Kirkmichael. Like the Missouri, these are short RIB rides from Trearddur Bay. The Kirkmichael lies a mere 300m off the end of Holyhead breakwater.
Wrecks for more experienced divers include the Apapa, a steamship carrying tin ore and silver coin which lies at 40-48m, and the Derbent, 14m proud of a seabed at 43m.
Stephen Knight feels that the accessibility of the sites around Anglesey is a strong point in its favour - and one reason why he has returned here. At a lot of places, you are looking for somewhere to park and get in the water - but here you can almost get in anywhere.
Anglesey Diver Training College is a BSAC Premier School. It can provide fills and has information on accommodation. Anglesey Diver Training College, Porthdafarch Road, Trearddur Bay, Anglesey LL65 2LP (tel. 01407 764545).

Harbour Highlights  
Mackenzie Pier, Holyhead Harbour. 9pm. The sun has set and the only light comes from the weak glow of a solitary lamp at the end of the pier.
BSAC National Instructor Martin Sampson assured me we would be enjoying a great night dive - but I was sceptical. After all, the pier was small, the water only 6m deep, and I couldnt imagine there would be much to see. I was wrong.
We had been joined by Stephen Knight and Vince Hall from South Gloucester BSAC and agreed we would wait 10 minutes before following them in.
They splashed noisily into the water and we clambered down the pier steps, watching the ghostly glows from their torches disappear into the inky blackness.
Watch your footing: the steps are slippery, Martin warned as I struggled to slip my fin straps over my ankles. The cold water slapped my face as I turned my torch on and, once my eyes adjusted to the fierce beam, we slipped to the bottom.
This was my first night dive at sea and it was an eerie experience. My strobe flashed just outside my field of view and I could hear my breathing coming in steady gasps. The sea bed was covered by fronds of kelp which swayed to and fro in the water, grabbing our legs as we began our course around the piers outer edge.
It would be possible to swim around Mackenzie Pier in five minutes - but this is not a dive to be hurried. The walls teem with life. Our torch beams ran along the wall picking out hundreds of frantically feeding barnacles. They seem like lifeless pimples of rock during the day, but at night they erupt in a feeding frenzy. Their tentacles flick out of their shells, grabbing plankton with the sort of enthusiasm Billy Bunter reserves for cream cakes.
Red-eyed swimming crabs glared at us and shrimps, or the vivid orange and blue markings of a squat lobster, were picked out by our torch beams from nooks and crannies.
Large pink shrimp drifted in and out of view and I spotted flatfish hiding deep in underwater crevices. A tiny spider crab perched on a rock, and a fan worms tentacles grabbed at passing food.
The beauty of this dive is that you can relax and, with a maximum depth of 6m, your only worry is whether you can tear your eyes away from the sea life to check your air gauge.