ONE OF THE BENEFITS FOR DIVERS visiting the Skomer Marine Nature Reserve is the resident team of Marine Conservation Officers from the Countryside Council for Wales, all marine scientists and divers. The team interacts with the public through its patrols and interviews of visiting boats and divers.
Those who pay a bit more attention will notice the team diving on their regular survey sites (DIVER, July 2004).
And divers who use the beach at Martins Haven may take the time to look at the marine reserve display on the way to the beach.
I dive in the area almost every year, and it was on last years trip that I noticed a new part of the display - a computer-generated fly-through animation from Wooltack Point on the mainland across Jack Sound to Rye Rocks on the north side of Skomer, then back and south through Little Sound, round the south of Midland Isle and back up Jack Sound to Wooltack Point.
The remarkable thing about the fly-through was that the sea had been stripped away, so we were flying across a rendition of the seabed. There was even an outline of the wreck of the Lucy just off Rye Rocks (Wreck Tour 3, May 1999).
It got me thinking about some places to dive that I had not tried before, and also about where else the Marine Nature Reserve may have similar data.
Its in such situations that the really big benefit of the resident team of conservation officers comes to hand. If you have any questions about the Marine Nature Reserve, marine biology or diving in the area, the experts are on hand to provide answers.
The location that particularly interested me was the Garland Stone and the north-west side of Skomer Island. The reef running north from behind the Garland Stone has long been a favourite dive site of mine, and while I had a mental picture of the reef, a chance to see it accurately mapped was too good to miss. Some time ago I had helped with an illustration of Jack Sound (DIVER, October 1998) and a similar illustration of the Garland Stone had long been rattling around in the back of my head.
Conservation officers Blaise Bullimore and Phil Newman explained the details. The Marine Nature Reserve has a multibeam sonar survey of nearly all of the marine reserve to a resolution of 1m in depth and distance, the main gaps being in very shallow water into which they couldnt take the survey boat. So the reefs surrounding the Garland Stone and the west end of Skomer were included in the coverage.

Computer slave
I begged the help of their colleague Mike Camplin, who had generated the fly-through animation of Jack Sound and is the expert on the survey database.
Mike really got into the project, and started generating images of the Garland Stone and west end of Skomer from the viewpoint that interested me.
It was a slightly different project to the Jack Sound fly-through, as I needed a high-resolution still view rather than a TV-resolution animation.
So Mike created the view for our illustration overleaf - which is a rather short way of thanking him for many hours spent slaving over a hot computer.
This brings me to a description of a long-time favourite dive, the Garland Stone Reef.
On the illustration, this is marked as route A, with the shallow rocks that just wash the surface marked by + rock symbols, because the start point for the dive is one of the places the multi-beam sonar survey boat couldnt go.
The best slack water for this dive is 2.5 hours after low-water Milford Haven, though it can be slack enough to dive at two hours after. As the flood tide picks up, the Garland Stone provides some shelter and extends slack water on the reef.
The opposite high-water slack is far shorter, and carries the risk of ascending divers being carried through the channel between the Garland Stone and Skomer Island, which is hard on the cover-boat.
In fact, if you want to dive on the opposite slack, 2.5 hours after high water, a safer dive is Pains Rock, a few hundred metres to the south-west (B). Pains Rock benefits from an extended slack and some shelter from Garland Stone on the ebb tide.
Arriving on site, the rocks at the end of the reef will be just breaking the surface, often with a few seals hauled out. The best start point is a rock perhaps half a metre below the surface, about a third of the way back to the Garland Stone (A).

Green to pink
The vertical scale on the under-water part of the illustration is greatly exaggerated, so it is only 10-15m down the face of the rock to the main ridge of the reef.
The underwater colouring of the illustration shows zones of marine life, from greens and reds for kelp to pink encrusting algae, and grey for all the sessile animals in deeper water. The sandy colour is used for relatively flat areas, regardless of depth, and in many cases will actually be rocks.
The basic route for the dive is to drop off either side of the ridge, pick a depth on the wall, follow it round the end of the ridge, then ascend the opposite side. Navigating is not rocket science. Its the sort of route that can be followed in either direction, though I usually prefer to descend on the east side of the ridge and ascend the west side.
The wall is a mass of anemones, mostly of the dark-coloured variation of Sagitaria elegans (I dont think it has a common name) which, while often looking like dark rock in natural light, shows up as quite pretty with a dive light.
There are also patches of daisy anemones, clumps of dead mens fingers and very occasional clumps of plumose anemones.
The upper edges of the wall and the end of the ridge tend to be dominated by brown carpets of hydroids, always worth a close look for some of the better-disguised nudibranchs. On this dive, the hydroids are also worth studying for colonies of ghost shrimps, almost transparent and only 1-2cm long, each hanging on to the top of a hydroid stalk, waving its arms in the current and boxing with others that waft too close.
Rounding the end of the ridge, you can pick your depth from 25 to 40m, with 30m or so being a nice compromise. I often used to find octopus here, but have not seen any for a few years.
Coming back in along the west side of the ridge, the wall leads into a canyon (A1) which narrows and is then blocked by a fallen boulder, leaving a swim-through beneath and then up. This is why I prefer the east-to-west direction for the route. Its far easier to enter the cave from the canyon and exit through the roof than vice versa. The cracks at the back of the cave are often inhabited by conger eels.
The top of the ridge (A2) is another mass of hydroids, sponges, dead mens fingers and anemones - this time mostly dahlia, with a few patches of jewel anemones and occasional cup corals. There may be patches of mussels, but this varies from year to year.

Crab explosion
Since tangle-netting was banned, the area has seen a population explosion of spider-crabs. Nowhere is better for finding them than along the top of this ridge and into the shallower reef above.
Plenty of swimming crabs and edible crabs are wedged into shallow cracks in the rocks, but remember that this is a no-take marine reserve.
With a wealth of nudibranchs, plenty of wrasse, snoozing dogfish and occasionally crawfish, the top of the ridge is a great dive in itself for those who want something shallower. Its also easy enough to pop a delayed SMB to end the dive here, but allow time to navigate back to the rocks where a shallow wall leads right to the surface, with more life to study while decompressing.
Otherwise follow the line of the canyon of the boulder cave into the shallows, where it widens into a rocky and sandy slope across the reef (A3), not shown above as manoeuvring the multi-beam sonar survey boat among the rocks was not safe.
Its a place for both tiny and big life, ranging from sea-spiders to a tug on the fins from one of the seals that haul out on the rocks. Having said that, seal encounters are much rarer here than among the much larger seal colonies found on other islands in the area.
For those wanting more time at depth, follow the wall out along the Garland Stone (A4). Its still a good dive, but the sheer density of marine life begins to fade compared to that on the ridge and the walls either side of it.
I should note that the west face of the Garland Stone (C) is disappointing compared to the Garland Stone Reef. Fully exposed to winter storms from the Atlantic, it is pretty much scoured. Due to some quirk of the waves, Pains Rock (B), further along the coast of Skomer, is a better dive, though you still have to go deep to get below the scoured region.
For a deeper challenge, drop off the end of the ridge and follow the seabed out (A5) at 40-42m. It soon leads to a detached pinnacle of rock that tops out at round about 34m. Marine life is similar to that on the end of the ridge, but in good viz the view is even better.
The final variation is to do the circuit in the opposite direction, then leave the wall on the east side of the ridge at 20m or so and follow across the slope of small boulders to the next ridge out to the east (A6). Among these boulders is the most likely place to see lobster, This brings me back to the wonder of the multi-beam sonar survey. Until I saw the 3D view, I didnt even suspect that there was another ridge further to the east (D).
Likewise, I never suspected the existence of the deeper reef south of Pains Rock (E). There are also several other interesting-looking reefs that show up on the survey in other parts of the Skomer Marine Nature Reserve.
Nevertheless, the ridge (D) to the east of the Garland Stone Reef looks like botha promising and relatively easy target for my next visit to Skomer. By the time you read this, I probably will have dived it!

Ghost shrimps standing at the top of their hydroids.
Above the start point for diving the Garland Stone Reef.
garden of dead mens fingers, hydroids and anemones along the top of the ridge


GETTING THERE: M4 and A40 to Haverfordwest, then B4327 to Dale and Martins Haven or B4341 to Broad Haven. For Neyland, leave A40 on A477 to Pembroke Dock, then cross the bridge to Neyland and follow signs for the marina.
DIVING & AIR: Pembrokeshire Dive Charters, 01437 781569, www.gopdc.co.uk. Dive in 2 Pembrokeshire, 01646 636684, www.dive-in2-pembrokeshire.com. West Wales Divers, 01437 781457, www.westwalesdivers.co.uk.
LAUNCHING: There are slips at Neyland and Dale and beach launching at Broad Haven. Martins Haven is best used as a staging point for divers, though small boats can be carried down the beach by hand.
FURTHER INFORMATION: Admiralty Chart No 2878 Approaches to Milford Haven. Ordnance Survey Map No 157, St Davids and Haverfordwest Area. Skomer Marine Nature Reserve Information for Divers includes detailed slack-water charts. Countryside Council for Wales, www.ccw.gov.uk