THE cave is at 6m directly beneath the cliffs, with a window at one end leading back to the open sea. When the surge is not too strong, you can dive right through it. Young, playful seals will often dart in and out of the cave with you, playing a game of hide and seek - they sneak up on you and speed off as soon as they have been spotted.
The site, known as the Mill Door, is half way along the west coast of the Isle of May, at the mouth of the Firth of Forth in Scotland. Shoals of pollack and saithe mill around the scenic archways and stacks and, if you are quick, you might spot a few guillemots as they shoot past you in search of dinner - they are good underwater swimmers and can dive to unbelievable depths.
The island, 5 miles from the fishing harbour of Anstruther, was declared a nature reserve in 1956. For much of the year it has one of Scotlands largest grey seal colonies, and is home to one of the UKs most concentrated populations of nesting and migrating seabirds.
The island is much longer than it is wide. On the west coast are beautiful, rugged 45m cliffs, with ledges and crevices which make ideal nesting sites for shags, guillemots, kittiwakes and razorbills. On the east coast the scenery is less dramatic, with grassy banks gently sloping towards the sea.
As you approach the island from Anstruther, you first see the scenic cliffs of the western side. It is important to watch for seabirds in the water, as divers have gained a reputation for driving their boats too fast through the seabird rafts, injuring and stressing the birds. Be aware that nature wardens stationed on the island are keeping watch.
Some of the best diving can be found beneath the west shore cliffs. The scenery here is breathtaking - there are birds everywhere, so many that it is wise to wear a hat while on the boat, or you may end up with something unwelcome landing on your head.
The Isle of May was home to Scotlands first lighthouse in 1636, and the remains can be seen today up on the plateau. The current lighthouse was built in 1812 and is visible for 26 miles on a clear night. You can also see the remains of the old Priory, dating back to the 12th century. The Monks who lived there are said to have kept a light burning round the clock to guide pilgrims safely past the island to shrines in St Andrews on the mainland.
The sheltered waters just off the west-end landing site at Altarstanes are ideal for your first dive. Here you find the wreck of the Anlaby, a British steamer that ran aground in thick fog in August 1873 carrying a cargo of coal. Today she is well broken up but makes an interesting dive, with shoals of pollack and friendly ballan wrasse that like to be hand-fed. The bulk of the wreck lies in 18m, with her propeller and rudder extending from her iron ribs.

Heading south from Altarstanes, a boulder slope leads from the wall at 10m down to sand and shale at 20m. Here you come across some extremely large boulders covered in deadmens fingers and anemones, interspersed with wolf fish, lobster, ling and conger eels. There tend to be strong currents here, so it is wise to do a drift dive.
When winds allow, there is some excellent diving along the south-west corner of the island around to South Ness. There are gullies in just 10m of water, covered in anemones and lined with kelp, and seals often haul themselves off the nearby rocks to join divers.
Towards the south-east end of the island the gullies open out to a kelp forest, before deepening into a series of steps which drop sharply to 30m. In good visibility this is an excellent dive. Red coraline algae makes the rocks look pink, and the orange deadmens fingers seem to stand out all the more as a result. You can sometimes find large starfish, edible crabs and squat lobsters here.
To the south-west of the island, about half a mile out, the wreck of the Primrose lies at 30m on a silty bottom. She is a steel-hulled fishing trawler sunk in 1904, in fairly good condition, although her main superstructure has collapsed. She is a spectacular dive, crawling in life, but can be quite a challenge due to strong currents and only a small window of slack water. Look out for ling, conger eels and pollack.
Along the east coast, there are fewer currents and the dive sites are
protected from prevailing winds. The marine life is not so noteworthy on this side of the island but there are plenty of wrecks to explore.
Just up from Kirkhaven harbour, a series of rocks known as The Pillow boasts wreckage thought to belong to the steel steamship Scotland, which ran aground in 1916. She was carrying oak barrels, paper and three small motor boats, but to this day the bulk of the wreck remains undiscovered.
Up from Kirkhaven harbour, scattered along the shore, are the remains of the steam yacht, Island. She belonged to the Danish royal family and was on her way from Copenhagen to Leith on 13 April, 1937, when she lost her way in thick fog. More of her remains can be found spread over the seabed between 15m and 20m. Up from the Kirkhaven towards East Tarbet, the bottom is particularly scenic, with a fairly steep sloping wall down to 26m. You can find urchins and starfish on the rocky ledges and brittle stars and edible crabs on the sandy bottom.
Just up from East Tarbet are the scattered remains of the steamship Jasper, which ran aground in 1894 and broke up in shallow water. Nearby is the schooner Linnet, sunk in 1877.
The north-west rocks around North Ness have become a graveyard for ships - more than half a dozen wrecks lie scattered over a fairly small area. There are strong currents here and many submerged rocks. Most of the wrecks lie well broken up in shallow water, but the Mars and the Thomas Devlin lie slightly deeper at 13m. A large section of the Thomas Devlin, a fishing trawler from Granton, can be seen wedged between North Ness and Mars Rock. There are some particularly scenic rocky gullies and archways above 10m that are sheltered from the current, and this is one of the best places to dive with seals.
If you go deeper, you will find thick carpets of brittle stars, giant dahlia anemones and a variety of crabs, including swimming, edible and spider crabs, on a steeply sloping sandy bottom. A mile or so offshore you will find some exciting wrecks, a few of which are almost completely intact. Because they are deep and often in areas of strong current, they are suitable only for the more experienced diver.
The 38m steamship Mallard was carrying coal from Dysart to Peterhead when she sank approximately one mile north-west of the island. She was found during a naval exercise in 1989, sitting upright in 42m on a sandy shingle bottom. She is still very intact and the few people who have dived here have raved about it.
To the east of the Mallard is the steam trawler Northumbria, which sank in 33m on 3 March, 1917, after hitting a mine. Her boilers stand upright but the rest of the wreck has collapsed.

Many Allied ships were torpedoed during World War 2 by the dreaded German U-Boats, which actively patrolled up and down the Firth of Forth. Two steamships, the British Avondale Park and the Norwegian Sneland 1, were particularly unlucky. They were torpedoed by a U-boat one and a half miles off the island on 6 May, 1945, at 11am - one hour before the end of the war.
Both ships are reported to be lying in 55m on a silty bottom. A few divers have attempted to dive the Avondale Park - at 97m in length and still intact, she is a spectacular wreck, but a challenging one due to her depth.
Two German U-boats were sunk off the island. The U-63 was attacked by two British armed trawlers on 20 January, 1918. She is lying in 52m just over 6 miles south-east of the island. The U-12 lies a couple of miles further out and a couple of metres deeper. The U-77 lies further south towards Dunbar in shallower water.
Two British K-class submarines lie fairly close to the island. They were lost in 1918, during a massive naval exercise that went tragically wrong (see panel). Both submarines can be found in around 55m on a muddy bottom, 13 miles east of Fife Ness.
The K-4 was broken in two, but the K-17 is still intact and makes a fantastic dive. The conning tower is bent over and broken open, allowing divers to see right inside. You can also see cups and dinner plates still stacked on top of each other, as well as the control panel.
The currents here are not too strong, but the wreck is deep and dark and should only be dived with proper planning and safety precautions.

K-Class Chaos!  
A botched naval exercise off the Isle of May in 1918, costing 100 lives, was hushed up. The remains of two submarines, the K-4 and the K-17 (above) mark the site of this ghastly blunder

NINE K-class submarines, numerous destroyers and two flotillas of ships from Rosyth were involved in the wartime exercise on 31 January, 1918. It had been kept so secret that not even a group of Royal Navy minesweepers patrolling the sea just a couple of miles off the Isle of May were aware of it.
It was a misty night, all navigation lights were switched off and radio silence was observed. With so many ships in one area, it was not surprising that total chaos resulted. There were several fatal collisions and two K-class submarines were sunk. The K-4 was rammed by the K-6, and she sank with all on board. The K-17 was hit by HMS Fearless; although she did not sink immediately and her 56 crew managed to escape, only eight survived in the chaos and confusion which followed. The battleships and destroyers following HMS Fearless arrived on the scene at a speed of 21 knots. They passed over the area where the K-17 had gone down - so fast that many of the men swimming in the water were sucked under and drowned. News of the incident was suppressed. One hundred men lost their lives and several ships and submarines were damaged.



GETTING THERE: Launch from Anstruther harbour. Fees are 4.50. Boats can only get into the harbour approximately three hours either side of high tide, so plan ahead.
DIVE FACILITY: Calypso Marine (01383 413 509) operates a charter boat service for divers from North Queensferry or Anstruther . Blue Dolphin (0131 661 3321) and Edinburgh Dive Centre (0131 229 4838) co-ordinate trips for individuals and small groups.
FURTHER READING: Dive Scotland -Volume III - The Northern Isles and East Scotland by Gordon Ridley; Shipwrecks of the Forth by Bob Baird (Nekton Books)
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