Profile: Rod Macdonald, diver

As we arrived in the Gulf of Corryvreckan, everyone on the boat fell silent. The gallows humour petered out as an apprehensive and nervous silence enveloped The Porpoise. This was a special place – one of the most foreboding and eerie places I have been in my life. The gulf simply seemed filled with doom, broken only by the cries of a few seagulls. We could see the much-fabled standing waves marking the spot where the pinnacle stood, ominously hidden in the depths.

David Ainsley manoeuvred his boat into position above the pinnacle, and a very heavy shot, made up of two old iron railway grips, was dropped over the side and plunged down into the depths. Once the shot had landed and snagged, the current whipped the rope tight. White water broke around the buoys as the current worked on them, leaving a huge rippling wake as though they were being pulled through the water at speed. The Porpoise would not be tying up to the downline, for even at the weakest tides there is never a period of absolute slack water. There is only a short window of about ten minutes of relative slack that comes about every six hours as the tide turns. The rest of the time, the force of moving water would work on the hull of the boat with so much strength that even our heavy shot would be easily dragged off.

To get the ten minutes of slack water for the divers down on the pinnacle, we would have to start the dive beforehand – when the tide was still running.

Once all the divers were prepped, the first two took their positions on the gunwales of the boat. Ainsley came out from the wheelhouse to give us a final briefing on the conditions and how the dive had to be run. He told us the tide was now starting to drop away. After the short period of slack, it would pick up fiercely in the opposite direction – and it would be time to get out of there and start the ascent.

A warning sign that the tide was about to turn would be when all the small crabs on the pinnacle darted for cover. They presumably had learnt through experience that if they didn’t get tucked away in some nook or cranny they would end up being swept over the side of the pinnacle for a 200-metre fall into the chasm. That would be a long climb back up for a wee crab.

We were ominously told that when our air bubbles started going downwards we should get the hell out of there – that would mean the current was escalating dramatically. We were told to put buoyant gas into everything we could, by bleeding air into our drysuits, into our buoyancy wings and by sending up our deco bags on our reels – together, that should be sufficient to support us and get us clear of the down currents.

Finally, Ainsley added a sobering warning. “Conditions today are not ideal – no one is forced to go in on this dive. There is no pressure on anybody to do so.” But we were all now committed and psyched up. There was no going back – none of us was going to wimp out.

Ainsley took The Porpoise up beside the buoys and was able to assess the tidal flow as being between 2.4 and 2.9 knots (a diver can only swim against 0.5 knots of current at best). He then took the boat about 30 feet up-current, to where he would drop us. By the time we were in the water and had righted ourselves, we should be drifting up to the buoys. It was time to go – the dive was on.

The first two divers rolled backwards into the water on Ainsley’s signal, righted themselves and grabbed hold of the shot-line as they drifted with the current. A quick round of ‘OK’ signals to each other and the boat and they slipped under the water and started the descent to the pinnacle.

Once they had cleared the buoys, it was time for Dave Hadden and myself to go. I pulled myself awkwardly up from the bench where I had got kitted up and made my way to the gunwale. It was hard work in a pitching boat, carrying two 12-litre tanks on my back, two nine-litre tanks of deco mix, one under either arm, my weights and all the other paraphernalia necessary to survive in the depths. I sat down on the gunwale and Hadden clumped down beside me. The skipper gave the signal that we were in position again and, hearts racing, Hadden and I rolled over backwards, dropping over the side of the boat heavily into the water a few feet below.

As the usual explosion of white water and bubbles that greets a diver on entry disappeared, I righted myself quickly and looked down-current, searching for the buoys and line. All my earlier fears and foreboding had disappeared. I was preoccupied with the mechanics of the dive, of getting to the shot-line and not missing it. Sure enough, I was drifting towards the buoys and could see the shot-line leading down from them into the abyss. The underwater visibility looked good – at least 25 metres – and I could see the bubble streams rising from the two divers ahead of and below me.

As soon as I grabbed the shot-line, the current that had been my friend in drifting me on to the rope became my enemy, and swung me round so my legs streamed out down-current. I kept a grip – if I let go I would be drifting very quickly towards America. I dumped excess buoyant air from my suit and wings and started to laboriously make the descent, hand over hand, inch by inch.

It took Hadden and I just a few minutes to haul our way down to the top of the pinnacle, and we found that, although it is at a depth of 30 metres, the shot had snagged down one side of it, at about 40 metres.

Initially I thought the pinnacle was devoid of life, seemingly scoured clean by the current. But on closer examination, I could see there was a fine mat of tiny filter-feeder organisms such as anemones, sponges and soft corals. All were noticeably smaller than their counterparts elsewhere in Scottish waters. Larger specimens are perhaps swept away by the current, or perhaps they have just evolved to be smaller to enable them to survive in this unique habitat. Because of the depth, the top of the pinnacle was clear and unobstructed by any kelp forests. Kelp fronds usually peter out at about 15 metres.

Large, smooth potholes four or five feet across peppered the surface of the pinnacle, where small stones had lodged in cracks or crevices and were then remorselessly ground round and round by the currents. Over a long period of time, these small stones had carved out six-foot-deep potholes.

There seemed to be no fish life, perhaps because there was no prey or food worthy of eating here. A few small crabs went about their business here and there.

Hadden and I circumnavigated the pinnacle at a depth of about 45 metres and then headed up, as planned, to its top plateau. We were conscious of trying to avoid spending too long at depth, as that would rack up lengthy decompression stops for the ascent. We kept a careful eye on our dive computers as the minutes ticked away.

In glorious 25-metre visibility, all three pairs of divers gradually collected on the top of the pinnacle. It was an odd feeling to see all six of us there, and I imagined how it must have looked if you could somehow have stripped away the water. Six tiny specks of humanity, standing on the 100-foot-wide table top, of a 200-metre-high pinnacle.

As we collected on the plateau, I noticed a perceptible change in the direction of the current – it felt as if someone had thrown a big switch. One minute the tide was dropping off gently in the one direction; the next you could feel it starting to pick up rapidly in the other. There were titanic forces at work here.

I looked down at the rock I was resting on and, sure enough, as if on cue, the one or two small crabs around my feet just made their way into little crevices, braced out their claws and seemingly disappeared. In fact, all life seemed to disappear from the pinnacle simultaneously.

The all too brief moment of calm had passed and the residents of the pinnacle were preparing themselves for the next six hours in the maelstrom. If the locals were getting worried, I thought, our team of six divers should be getting out of there. Hadden and I, however, couldn’t resist the temptation to fan out to the edge and look over the side, down into the 200-metre abyss. Of course, in the limited visibility we could only see about 25 metres – deeper than that was just an ominous, uniform black. The bottom was well out of sight.

As we held on to rocks, I became aware that my exhaled bubbles had stopped rising upwards – as they had done throughout my diving career. For a second or two, some bubbles were held motionless in front of my face.

With my next exhaled breath, the bubbles started to slowly sink down over the side of the pinnacle. As I continued to breathe out, my bubbles started going downward increasingly vigorously. It was a very surreal experience and it was certainly time to get out of this dangerous place.

I looked at Hadden and gave the thumbs-up signal – which was returned with an ‘OK’ from Hadden. We prepared ourselves by pumping gas into our suits and wings until we were almost positively buoyant. We then each inflated our deco bags; the reels spun and chattered, paying out their thin line as the bags sped to the surface.

Once the bags hit the surface and the reels stopped paying out, it was time to go. Pumping even more gas into suit and wings, we let go of our rocky handholds, stood up and basically let the current get hold of us. We were swept instantly over the chasm of the Gulf of Corryvreckan. Our exhaust bubbles were still going downwards.

We had been warned the first ten metres of the ascent would be difficult, and right enough, as I stepped off the top of the pinnacle, it was as though 1,000 invisible hands were clutching at my legs and trying to pull me down. It was quite an unsettling feeling, and initially I had to fin hard to make any headway upwards. The task of managing the ascent, however, soon absorbed me as I kicked my legs and simultaneously wound in the slack on my reel, essentially winching myself up towards the surface.

Once I got ten metres from the top of the pinnacle, the current had already carried us so far downstream that we were starting to come out of the whirlpool. As I rose higher and got further away, the water seemed to settle down – and soon we were just into a regular free-hanging ascent on our deco bags and reels. We drifted free in the current, seemingly motionless but in reality speeding over the seabed at several knots in a fixed column of water.

As we all broke the surface and clambered back into the safety of The Porpoise, a sense of euphoria overwhelmed us. There was much manly banter and slapping of backs – a complete contrast to the silent mood that had overcome the team before the dive. We had successfully carried out perhaps the most challenging dive in British waters, into one of the last great, unexplored habitats on earth. We all realised it had gone so smoothly largely due to the professionalism and know-how of David Ainsley and team leader Graeme Bruce. They had made a potentially terrifying dive manageable. We had stood on the pinnacle and peered into the abyss. n

• The Darkness Below, by Rod Macdonald, £18.99, Whittles Publishing, is available to Scotland on Sunday readers for £15.99 (plus £1.95 p&p) by calling 01593 731333, or e-mailing [email protected]