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Tompot blennie at Trearddur Bay, Anglesey dive site - courtesy of Tony Gilbert
Fanworms at Trearddur Bay, Anglesey dive site - courtesy of Tony Gilbert

Scuba Diving North Wales, UK, Europe

Reader Reviews:

Dive Site: Trearddur Bay

Location: Anglesey, North Wales

Description: Shore dive

Depth: 5 - 10 metres (15 - 30 feet)

Visibility: 8 metres on average (26 feet)

Rating: ****

A consistently great dive and worth repeating in lieu of the plethora of macro life in and amongst the gullies. North Wales and Anglesey have some great dive sites both offshore and onshore, however for many Trearddur Bay shore dive is special. It encompasses much of the atypical marine life you'll see in this area, and is located amongst a "hotpotch" of gullies, mini-walls, trenches and holes. Many new divers are introduced to UK diving at this very place.

The downside of Trearddur Bay is its location in relation to the prevailing wind, so when the weather is all ruffled up so is the bay. If conditions allow though, the jewel in the crown of Anglesey doth shine. It has to be said that Anglesey received bad press several years back when in 1990 a big storm made short work of some of the village of Towyn on the mainland near Conwy. The repercussions of which still reverberate around today in the minds of some and many divers stayed away for a while because of the lowered visibility. Things have got back to some form of normality, and I have been diving here since 1996. On occasions the visibility (always in divers minds) stretched to a whacking 20m in 2005 for a few weeks but the average is more likely to be around 8m. Plankton blooms occur around June, and again a small one in mid-August.

Having dived this many times over, and even in early March when large icicles have begun to drip off the nearby headland and the sand crunches with the ice it is possible to spot things out of the norm like huge herds of grazing red sea hares. Trearddur Bay is a bay within the main Penrhyn bay and on its southern flank is a headland known as Ravenspoint. Several dives can be made like Ravenspoint gully, or The Rocks, or Porth Diana Gully which is best accessed via high water.

Porth Diana Gully leads out to an underwater world which is full of marine life, the most popular route being around the nearby half-tide rocks. In 2006 we were able to complete a 108 minute dive in sparkling sunshine and good visibility. The dive starts on the Ravenspoint headland where a large grassy area allows room for kitting up. Some prefer the beach access and others pay to park & kit up in the nearby dive centre car park. For the vertically challenged diver, he/she has to negotiate some roughly hewn steps in the rocks, leading to the middle of the gully itself. At high water this is easily accessed but low water gives a problem of dryness and access best from beach. Don't be tempted to swim out around the small island formed by high water as it's a long swim across a shallow kelp bed!

Once paddling down the gully the steep sides are covered in barnacles & limpets, gradually giving way to a thick head of a kelp line which doesn't die off until below 8-10m and is usually restricted to the upper parts of the rocks as the remainder are vertical. With the ridge initially on the right the left is a mixture of seaweeds; lettuce and bladderwrack in amongst small smoothed pebbles, where dragonets and flatties prefer to be. Several enclaves of rock occur, as do numerous small horizontal fissures, all in 8m. It is best to take your time and explore these thoroughly as they contain plentiful supplies of velvet swimming crabs, tompot blennies and shrimps, all in a line! One rock hole is cylindrical and a ledge at 5m contains a variety of crabs, anemones and shrimps.

Continuing along the ridge for a time, a sharp right turn at about 50m out will ensure the diver encounters a series of deep cut fissures, which angle sharply into the rock. Many deadman's fingers and white actinothoe anemones adorn the outer and inner walls, lobster can be spotted as can dogfish but the most numerous animal has to be the ballan wrasse who charge around these underwater causeways with some speed.

The fissures are replaced by vertical rocks undercut sharply into dark maws that are difficult to get into so don't attempt it. Gradually the heading has changed from west to a more northerly one, as the diver comes about. Nudibranchs, such as Coryphella and Flabellina and sea hares can often be seen grazing the lower slopes of the rocks. Small green wrasse, pick their way across this landscape. The ridges start upwards and as the course becomes easterly a channel of sand forms amongst the thick clumps of kelp. Just a few metres below the surface a shelf of rock contains many crabs scuttling this way and that whilst wrasse patrol, all of which have an olive green hue to them in tune with the surrounding flora of bladderwrack. Eventually a southerly course has taken the diver the final part around the small islet and onto the beach at Porth Diana and exit.

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