SPECIAL AREAS OF CONSERVATION (SACS) are something gifted to us by the European Union under the Habitats Directive, which came into force in 1991. Countries that let their SACs become degraded are asking for big trouble from Brussels - the Habitats Directive has teeth.
Together with Marine Conservation Zones or MCZs (see accompanying article by Joana Doyle), SACs will contribute to the ecologically coherent network of well-managed marine protected areas that the UK Government is committed to introduce by 2012.
Prawle Point to Plymouth and Eddystone is just one of five reef areas identified as potential new SACs on which Natural England will consult.
To my mind, the area should also be a Marine Conservation Zone, and therefore better supported by a range of protection measures.
Furthermore, limited areas in it should be Highly Protected.
Divers benefit from protected areas that maintain the diversity and beauty of marine life. The underwater scenery and the range of reef species out of Plymouth is fantastic, and many species are colourful, exotic, fragile and often rare.
Here are some the features that demonstrate the richness and variety of the proposed SAC:

This area from the Mew Stone off Wembury to Stoke Point includes broken shale rocks that create gullies, overhangs and areas of sandy rocks that are worth a closer look.
Peer under the overhangs and you may see nationally scarce species such
as the pink sea fingers Parerthropodium hibernicum.
Drift over the sponge gardens at Stoke Point and see fragile and colourful branching sponges that may be hundreds of years old and, growing through the sprinkling of sand, the twig-like growths of the nationally rare sponge Adreus fascicularis.
Explore the inshore shallow gullies to find colonies of the nationally scarce scarlet and gold star coral (Balanophyllia regia). Fish are abundant, with colourful wrasse and the ubiquitous prize-winning tompot blennies just asking you to take their picture.

The submerged cliff-line offshore from the Sound is not for the inexperienced, but worth working up to.
Here, you encounter buttresses of sandstone up to 5m high capped by red sea fingers (Alcyonium glomeratum), and dense sea fans (Eunicella verrucosa).
Then, follow deep incisions in the rock to narrow canyons where, with luck, you can see sensitive colonies of the nationally rare sunset coral Leptopsammia pruvoti and colourful colonies of the yellow cluster anemone Parazoanthus axinellae, often growing on branching sponges.
In late 2008, there was a very large settlement of the bizarre and nationally scarce football sea squirt (Diazona violacea), so that, rather than hoping to see as many as four on a dive, you can see five or six on one small rock wall.

Eddystone offers a range of diving, including tucking in to the west side when the tide is running for some of the most spectacular marine life - made more so by the brilliance of the white shell sand between reefs.
Sea fans are abundant, and fish prolific. Both species of soft corals, dead mens fingers (Alcyonium digitatum) and red sea fingers (Alcyonium glomeratum), can be seen. And look out for the false cowrie, Simnia patula, which feeds on them and lays its brown eggs conspicuously on the white ones.
Seafan nudibranchs (Tritonia nilsohndneri) are usually first seen when you spot the egg coils on the branches of the fans - they have years of abundance and years of scarceness.

This is well worth the effort of reaching for a spectacular drop-off into deep water, but the top is extensive and shallow, so should not be intimidating to reasonably experienced beginners.
Head out through the gullies and over cliffs dominated by jewel anemones (Corynactis viridis), with headlands supporting groups of plumose anemones (Metridium senile).
Ascend via the shallow areas, where growth of kelp and other seaweeds is overwhelmed by elegant anemones (Sagartia elegans), seafans and the infrequently seen Indian feathers hydroid (Gymnangium montagui).
Look out for the distinctive tassles of the brown seaweed Carpomitra costata, which is nationally rare.

Get there if you can, as its both spectacular and very different in character to other reefs, though its not for the inexperienced. The rock looks like a granite tor, although it is mica-schist, and the jewel anemone-covered cliffs drop precipitously from about 20m to more than 50m deep.
Purple volcano sponges, Haliclona viscosa, are abundant here, and its the only location out of Plymouth where I have seen the large cushion starfish Porania pulvillus.
Pink seafans occur especially in rock coves where, if you look closely at the branches, you should see the nationally scarce seafan anemone Amphianthus dohrnii and a false cowrie, Simnia sp, shaped like a small spindle. It may be a species new to science.
Information on the biology of areas out of Plymouth has benefited from studies extending back 100 years - from the Marine Biological Association, from when nature conservation agencies in England undertook or commissioned diving surveys, from the Devon Wildlife Trusts work and, in recent years, from Seasearch surveys.
Perversely, none of my comments about richness, rarity, fragility, sensitivity and so on are relevant when applying criteria from the Habitats Directive. The habitat has to be a reef, the bigger the better to satisfy Brussels.
But we do try to improve on a directive that was drafted 20 years ago. The criteria developed to identify MCZs are well thought-through and, on the whole, scientifically sound.
Trouble is, there remain big gaps in our knowledge of what marine life is where in inshore waters, gaps that cant be filled by the favoured techniques of acoustic survey and drop-down video.
There is no sign that the relevant agencies will seriously attempt to fill these gaps with in situ surveys using diving biologists in English waters.
Meanwhile, divers should support the proposed Prawle Point to Plymouth and Eddystone SAC and the introduction of measures to identify and protect MCZs.

FURTHER INFORMATION - Consultation: www.naturalengland.org.uk/ourwork/marine/sacconsultation. Dive sites: www.plymouthdivers.org.uk.
PowerPoint Presentation: www.ukmpas.org/presentations.
Help with surveys:
www.seasearch.org.uk, www.marlin.ac.uk