THE SPECTACULAR DRIVE along the A87 through Glenshiel, where the Five Sisters of Kintail tower high above you, brings you to Loch Duich - and the home of some excellent muck diving.
Loch Duich is probably best known for picturesque Castle Eileen Donan, situated at the confluence of Lochs Duich, Long and Alsh. It has long been used to sell scenic Scotland to tourists, but is probably remembered by many as a backdrop for several fabulous scenes in the film Highlander.
However, for anyone who enjoys seeing sea pens, Loch Duich is the place to find them. All three types - tall, slender and the very beautiful phosphorescent - can be found here, sometimes all at the same dive site.
Sea pens are colonial marine cnidarians. They have a central stalk, the bottom of which is free of polyps and buried in the soft sediment of the seabed. The top part either bears polyps directly on the stalk itself, or on pairs of branches.
Tall sea pens, which can grow up to 2m high, have a very feathery appearance and can bend gently in the current. The less conspicuous slender sea pens stand ramrod straight, merely leaning over slightly as the current begins to run. These smaller sea pens can grow up to 60cm high and appear fluffy, but the last couple of centimetres at the top of the stalk are bare.
The phosphorescent sea pen is probably the most beautiful variety, and does indeed look like a quill pen. It is usually pale pink or reddish, and is capable of a certain amount of luminescence.
These unique creatures need the type of muddy, silty slopes that can be found in many places in Loch Duich, particularly those sites nearer the head of the loch. However, there are also many small rocky reefs along its shores.
Dives are typically dark after the first 10m or so, largely due to the peaty run-off from the hills. However, visibility has always been a reasonable 5-6m or more whenever I have dived here.

THERE ARE NUMEROUS PLACES along the western shore where you can just park up and drop into the water to explore, but the shingle beaches behind the Youth Hostel in Ratagan, and by the slipway in Letterfearn, make ideal entry points. Both have muddy slopes, with tall sea pens around 1m high.
To get the best of both worlds, enter the water near the Letterfearn slipway and swim straight out over the weed and down a gentle slope.
At around 25m, you will find tall sea pens bending their slender bodies to the movement of the water, ideally placed to catch passing nutrients as the tide comes and goes.
Turning left, you will find a muddy environment with scallops and hermit crabs strolling around the delicate loch anemones. Rather bizarrely, several lavatories have been dumped here, and many long-clawed squat lobsters have set up home in them.
Turn right, however, and you will meet the small reef that continues the rock formation seen above the slip.
This reef disappears at around 20-25m and returns to the familiar muddy slope, but its rocks are covered with hairy brittlestars, beautiful translucent sea squirts and gaudy sunstars.
At the head of the loch is, as you would expect, another mud slope with an easy entry off the jetty in front of the Kintail Hotel. This is a very gentle slope and, despite swimming for some way, I have never achieved more than 15m at this site before having to turn round.
However, this is the only part of this loch in which I have seen dogfish. About half a dozen were just lying around, chilling out in one small area of mud.
Once again the seabed here is covered with holes, homes to gobies and Dublin Bay prawns. I also spotted several beautiful tub gurnards. These lovely fish appear to fly through the water on blue wings once disturbed.
A small road takes you down towards Inverinate Church, where there is convenient parking next to the loch in front of some houses. This is another site for seeing all three types of sea pen. It can be dived at any state of tide, and local use of the shingle beach for launching small boats has produced a weed-free area, making for safer entry.
At around 15-20m, slender sea pens start to appear. Their pale brown colour often makes them hard to see against the seabed, while the bare patch at the top of the central stalk gives them an unfinished look. Scattered around are phosphorescent sea pens, their pinkish glow making them easier to spot.
Then, moving a little deeper, you will find fluffy tall sea pens gently bending with the movement of the water.
Tall sea pens are usually spaced 1-2m apart, yet often appear as a white, feathery forest, growing to the edge of visibility. In the dark, by torchlight, the effect is surreal.
Also living in this loch is the fireworks anemone, found only in Scottish lochs and a few sheltered places in Ireland.
With a 30cm span and up to 200 tentacles, fireworks anemones are unmistakeable. Their white, brown and creamy colours contrast dramatically with the grey mud in which they grow.
While these dives near the head of the loch offer mud slopes, those towards its mouth on the east and west shores give you reefs, walls and drop-offs.
For the fit and adventurous the rocky walls (often called Dornie Corners) just before the castle, can be negotiated to dive the reefs below.
Some clubs use ropes to navigate the rocks, while others just climb down. However, these sites are probably most easily reached by boat, which can be launched from the slip further up the road in Dornie.

FOR THOSE WHO PREFER a more leisurely entry, there is a long lay-by about half a mile past the petrol station on the A87 as you drive towards the castle. It has space for eight vehicles.
Crossing the road here and skirting round the lochside barrier, you will find a muddy path leading to a shingle beach. At high tide there are rocks to support you while you don your fins, and no weed-covered surfaces to negotiate.
Head straight out down the steep, rocky slope, which gives way to shingle and finally muddy silt. Here you will find delicate loch anemones and perhaps, as I did, a cheeky hermit crab sitting atop one of the many scallops dotted around the seabed.
At around 18m is a small reef smothered in the hairy brittlestars that seem so prevalent in this loch. Many of these are out of sight between the cracks, legs protruding, waving in the currents to feed on passing nutrients.
Clusters of translucent sea squirts are attached to the rocks, wafted back and forth by the tide, while edible crabs lurk under small overhangs.
A similar dive can be had on the opposite shore near Letterfearn.
Drive through the small hamlet, and on the far side is a large, disused building. A notice asks you not to park in front of the brown doors, but there is room for a car or two to pull in here.
Follow the short path behind the building and down the rocks to find a suitable point to enter the water.
High-water slack is probably the best time to dive here, to avoid having to clamber over slippery rocks, and the current that can run a bit at mid tide. Swim out to 15-20m down a fairly steep mud slope, and once again you will find all three types of sea pen dotted around.
Having investigated these, you can either turn left or right to find a reef that stretches down to around 30m. Beyond this, the mud slope continues.
Both reefs on either side are covered with fluted sea squirts and the perfectly round spheres of football sea squirts.
Every crevice seems to be a home for a long-clawed squat lobster, while the rocks are covered with hairy common and black brittlestars.
Dotted here and there are cup corals like little gems stuck fast to the rocks. Dragonets lie stock-still, determined not to be seen, as wrasse work their way up and down the reef. Little sandy ledges are occupied by leopard-spotted gobies, which demonstrate one of the fastest disappearing acts on Earth should you approach for a photo.
There are one or two other places a little further along this road where you can slip into the water and find colourful reefs. However, it can be difficult to get down to the water, and kit has to be dropped off before parking further on.
Fairly sheltered, Loch Duich is a wonderful venue for year-round diving, although heavy rainfall and bad weather can reduce visibility. Its scenic location and historical associations also make it worth visiting should you have a non-diver in your group.

Nearest airfills, 5 Bells Diving, Lochcarron, www.5bellsdiving.com. Accommodation: B&Bs in Ratagan and the Kintail Hotel, www.kintaillodgehotel. co.uk. Tourist information: www.northhighlandsscotland.com