Diving is good. Really good. On a planet that has great wide open seas bursting with sunlight and life, it is a waste of time to do it in a cave. I dive with UBUC of Bristol because they taught me to dive and they are a sound club who do a lot of diving for not very much money. They have two elderly Zodiac inflatables, lots of miscellaneous gear and a compressor. We, eight of us on a grand tour trip, took it all to Scotland for eleven days in a hire van and on a trailer on the back of JL's land cruiser. We dived and did the necessary work to go diving so much each day that there was no time for anything else.

There were three of us in the van: Simon, Jamie and myself. And the land cruiser contained JL, Damian, Georgina, Andy and Jez. JL and Damian were much older than the rest of us, having cleared whole decades since they were students. Also, they are pretty hard case divers.

It was raining in Bristol but it was sunny when we rolled up to the first dive site at the edge of the Clyde. The idea of the trip was to do all the famous dives in Scotland in one go. Several of these were in the Clyde which, being a river estuary, is a horrible place to dive. I don't know why we went there. The sun for all its brightness did not penetrate more than twelve metres deep and the water was unbelievably cold. The diving was an exercise in extremes: I baked and basted in my own sweat in my 8 mm neoprene drysuit as the sun burned the skin of my face. I froze my nuts off underwater down below where it was so dark it might as well have been two o'clock in the morning. I waved my torch around as I followed the girders of the wreck of the Akka trying not to get too far from the shotline so that I could find my way back. Simon and I probably saw one tenth of one percent of it on that dive.

We stayed on the Clyde for two days. You could watch black submarines cruising out of Holy Loch past the derelict shipyards. I dived the Akka again, this time following Andy and Georgina in a threesome. We strayed qulte far across the wreck looking at the soft corals called Dead Man's Fingers and the crabs scuttling among them. These animals survive in permanent darkness like the life at the bottom of the ocean, although this life is only 26 metres down instead of two miles. As I was shining my torch around and following my buddies it occurred to me that in this darkness we might have accidentally entered the wreck without noticing. The idea petrified me. By now, if it had happened a few minutes ago, we would be too far in and it would be too late: our exit would be blocked by opaque clouds of silt. We would be reduced to scrambling around dark and freezing cold rooms for the remainder of our short lives until our torches and our air supplies expired.

I calmed myself down after several minutes. The surfaces we were coasting across were flowering with sea growths, sponges and white bloated dead men's fingers; this kind of life couldn't possibly exist in the stagnant water inside a sunken ship, could it? A little while later I raised my left hand and it clanged against a metal ceiling. I looked up and saw lots of dead man's fingers growing downwards from it. My preconceived nightmare flooded back to me. I entered a state of terror for a moment and then grabbed Andy's fin, and hauled him back to me. He looked at me and I jabbed at the ceiling several times signing to him to do something about it. In a cloud of hyperventilated bubbles and dislodged rust flakes, we got out. We were not far in. Georgina did not know why we cut the dive short and why I was so glad to get back to the surface. She could see no problem with being inside a pitch black wreck many metres from the light.

That night we camped in Glasgow's shagger's alley. There's one of these for every major town in the country. Aside from the used condoms everywhere you can see it at night when you drive down to the far end of the car park and your headlights light up the passenger seats all the way down the line. These are not good places to sleep because they are too busy; cars drive in and out of them all through the night like in a large bus terminal.

The next day were at Oban. There was no time to buy whisky as there was far too much diving to be done. We launched from Connell Bridge and motored out to the Breda. I know hardly anything about ships or even ship wrecks. Most wrecks that I have been to look like an assortment of girders scattered on the sea bed in a regular array. This wreck looked to me like a building. The roof was flat. If you went off one side it was a wall, and on the other side there seemed to be lower floors from which you could pass into and underneath where you had just been. Then when you returned to the top level again there were columns of bubbles escaping from tiny holes in it as the air you breathed while underneath percolated through.

There were four of us in each of the two Zodiacs. The diving was always done in two waves, one pair from each boat diving at a time. The pair left behind guards the boat and also helps haul the divers in at the end of their dive; it is nearly impossible to go from a position of bobbing around up to your neck in the sea with thirty pounds of lead round your waist and a big metal tank on your back to being up and inside the boat without some kind of help. By the time we had all finished our first dive, thirteen other dive boats had collected around the wreck. It was diver soup below; the sea was foaming with bubbles and there couldn't have been much to see for all the shit that was undoubtedly being kicked up by their presence.

Connell Bridge crosses the narrows of a large tidal loch. The current as you look over the bridge looks vicious as it flows past the banks and pillars. There are swirls of whirlpools and upwellings of water in it. Simon, being the careful person that he is, declined to dive here. The rest of us dropped ourselves in the current upstream. When Damian and I rolled backwards off the side of the boat we held hands and finned as hard as we could while still upside down until we hit our heads on the bottom. From there we were swept forwards along the loch bottom as hoards of tiny crabs tried to outrun us across the gravel. Suddenly the floor disappeared and we fell into a hole twenty metres deep lined with bare rock and mussels. This was qulte unexpected, though very compelling. No one managed to get under the bridge completely; everyone got spat out on the surface somewhat by then. Another dive on The Breda completed the day and we cleared off to Fort William for haggis and chips.

And from there to the Kyle of Lochalsh where the ferry to Skye departs.

Diving at depth out of sight of the surface is a strange thing to get used to. You have no contact with the outside world at all. Often a wreck, if it is frequently visited, has a permanent shotline on it: a rope tied to a part of it with a buoy at one end. You jump in the water, pull yourself down the rope and explore the wreck which, for all intents and purposes, is in another universe. Its only tangible connection to reality is via this line. At the end of the dive you have to find it and pull yourself back to the surface to rejoin the real world. If you miss it you have to make a free water ascent and spend time in limbo with no contact with anything in any direction. You hover in a boundless universe of murk. Only the reading on your depth gauge gives you any clue of where you are.

Diving the wreck of the Port Napia is a very rich experience because it is in shallow, clear water and spans the distance between the sea floor and the surface. The ship is entirely on its side so the top deck with its beautiful wooden panelling is like a wall as you swim past it. At the stern there is a wide, dark hole to swim into. You swim between two walls which are the floor and ceiling of one of the decks. The side of the ship that is on the surface has mostly decayed away to let sunlight stream into it past green fronds of kelp. It gives you the feeling that you are diving in a large aquarium. Georgina and I were able to reach the other decks via rust holes we could rise up and somersault headfirst into. In one of the rooms there was a long ladder which Georgina 'climbed' upwards; It remains a mystery to me how it came to be orientated the way it was considering the angle of the ship.

Port Napia was so good we dived it again in the afternoon for another furtle around starting at the mast which was horizontal. Several loops and dangling strands of rope hung from it. These may have been ordinary ropes at one time, but now the sea life had colonised them so heavily that they were well over a foot in diameter with squidgy sea growth. This stuff is very much like the lichen you get on rocks, but instead of being 0.1 of a millimetre high it is as tall as a cauliflower. I led Georgina into the darkest swim-through I have ever attempted; we proceeded down a railway-sized tunnel almost out of sight of daylight until we could just make out the faintest glow of a blue window up ahead of us, and went for it. I have heard that this strategy does not always work: you can get to the far end only to find that the hole that is letting in the light is too small to get through.

The next day we cleared off in the direction of Mull. The camping up till then had been in lay-bys and parking places. It was like being on the run, permanently moving on to the next place like a fugitive. It ground us down. The weather had changed and it was no longer sunny. Jez and Georgina took to standing in front of the exhaust pipe of the compressor to keep warm, not minding the carbon monoxide. My clothes became quite grim. My furry suit (divers call it a woolly bear) had the odour and warmth of a damp compost heap. People would hold their noses and be relieved after it was properly zipped up and sealed with me inside my drysult. And my jeans which I wore otherwise were becoming like the undressed hide of dead animal. My hair was all over the place and my skin was beginning to peel. Jez somehow managed to keep his appearance lovely all the time. His hair was clean and perfectly combed even when it wasn't. If the police stopped us or we ran out of fuel, he would be our spokesman or the man most likely to be able to hitch-hike to a petrol station.

A couple of medium good dives happened the next day in the drizzle in Ailort Loch. Jamie led me down a wall of writhing brittle stars, through a layer of pulsating jellyfish right to the silty floor at 30 metres. I have a problem with nitrogen - I get narcosis from it (or 'narked' as we say). Jacques Cousteau called this phenomenon the rapture of the deep. For me it sets in at about 28 metres, which isn't very deep by most people's reckoning, and it's not rapturous. I get this feeling of warmth all over my body and in my mind I am fearful that I am going to do something really stupid which will almost certainly wind up with me getting drowned. It happened again on this dive but it didn't seem too bad. In fact it was quite nice. I must be turning into a bit of a nitrogen junkie.

In the morning Jamie set up his fly trap by the side of the road. This was made from a bit of fly paper and a jar of three month old rotting pigs kidneys. For best results he uses the same meat all summer so that it gets really ripe and smelly. His work has something to do with genetic matching so he wanted flies from diiferent parts of the country. I think he is a fly and just likes the smell.

That evening we drove forever down Scottish 'A' roads which for the most part are single track and slow. At the end of the road there was practically nothing. JL somehow found a pub and had two pints of Guinness for supper while the rest of us cooked dinner and ate in the darkness. Jez and Georgina had brought two weeks worth of food with them in the form of Vesta curry type meals while the remaining five of us ate slop cooked by myself and Damian in his pressure cooker on his petrol burning death-trap stove. It took time to serve out the rice because Damian likes to rant and shout at you when you spill a single grain on the floor. Damian is very good at shouting and getting violent; he'd be too noisy and bad at taking orders to be in the army, but he'd do well as one of those men in the stock market who deal in incompatible computer equipment and Polish cucumbers. I could easily see him cornering the market on pickled gherkins one month and bringing a truckload along on the trip for us to eat for breakfast, lunch and dinner each day.

In the morning it was cold and raining again and we were all tired. Jamie read aloud from the book 'Safe Diving Practices' which contained the line: 'Divers should be warm and well rested before embarking on a dive.' This holiday was becoming a genuine ordeal. Two dives out at sea to the north of Ardnamurchan peninsula happened that day. One was at a place called Bo-Fascadale and the other was on Elizabeth Rock. Both were pinnacles some distance below the sea in the middle of nowhere which JL located with the use of a Global Positioning System and a sonar. Everybody else thought these were superb dives, but I was unconvinced. They were sheer vertical walls plastered with large dead man's fingers and nothing else. There were no creepy crawlies or fish around at all. You just go down to some depth and then zig-zag up the wall past this array of large, white bulbous growths. I surface with a bad headache both times.

It's quite common that I surface with a rotten headache after a dive. When I started diving I got one from biting too hard on the regulator mouthpiece throughout the dive because I was terrified of losing it. I've come up sick from bad air at least twice in the past. The headaches I now get tend to be due to dehydration, like the kind you get from a hang-over. The air from the aqua-lung is completely dry. It goes into and out of your lungs via your mouth and so dries your body out very quickiy. Whenever I drink enough water to avoid dehydration I always need a piss. Unfortunately the drysuit I wear is really hard to get into and out of and the chances of falling overboard in the process are too high. Just to rub it in, Damian always strips off his ultra-expensive drysuit to take piss before and after every dive. However, at the end of the day I've decided that I prefer to have a pain in my bladder than a pain in my head.

The weather for the rest of the trip was sunshine and showers. This is acceptable since you actually get some real sunshine between the showers. We dived in The Sound of Mull from then on, and it was good. I dived with Jez off Calve Island on another of those rock walls. Unlike Bo-Fascadale there was a bit more happening here. In all the cracks there were numerous fiddly little prawns standing there like prawns. Crabs crab-walked about among the vegetation without falling off. We pulled a feather star off the rock and watched it swim with a beautiful paddling motion of its fronds. Most starfish do bugger all - they are like lumps of oddly shaped flesh stuck to the ground. It's a shame you can't eat them (though I don'tknow why you can't) or we would have had more meat for dinner. I knocked a few sea urchins off the rock and watched them sink to the unspeakable depths below me in my torchlight I wondered what they were going to do down there and how they would know which direction to crawl to get back up to the wall. I saw about three fish on that dive, which is more than I have seen anywhere else in Scotland.

On the way back we did a mass dive on dregs at another underwater wall, starting with hardly any air in our tanks. I stayed down for ten minutes. There were sea squirts and worms waving their frilly bits out of narrow cracks. I snorkelled back to the boats and saw those kinds of jellyfish which look like they are wearing yellow intestines inside their transparent bodies. They each had a mop of tentacles below them infested with their own crowd of tiny fish.

My favourite dive of the entire trip occurred on the Risgi Pinnacle in the afternoon. The first wave of divers went down the shotline and went on the south side as it said to go in the guide book. JL and Jamie were among them and got bored with the muddy slope of gravel that was there and eventually swam around to the north side where they were to behold a wondrous sight. I went in with Jez, and Georgina went in with Andy, and we went round the pinnacle in opposite directions.

As we rounded the edge, there it was: an overhanging wall with white, grey, tan and pink plumoses growing all over it. The floor was thick with silt, but there were large boulders close by also rich with beautiful tall and slender plumoses. These creatures are like transparent ball gowns each about a foot high with frills at the top like a huge rose made of silk. I just had to touch and fondle them. We had fun there grovelling about on the floor, chasing squat lobsters out of their holes and getting some large scallops to swim up in the 'air'. Then we bumped ihto Andy and Georgina who flicked 'V's at us when they saw the monstrous cloud of shit and silt we had kicked up in the water behind us which they were now about to encounter. We were ashamed. We floated up the wall and continued at a higher level among a sea of plumoses. This was a dive I was very sad to end.

At this point in the trip I began to break official BSAC guidelines by not wearing a buoyancy compensator. The pleasure gained by this decision was surprisingly immense. There are four hoses which come off the top of my air tank. One goes to the regulator which gives air to the mouth so is quite important. The second goes to a pressure gauge which dangles about somewhere on my left hand side; I can find it now by reflex; it is usually reassuring to look at. The third hose comes round my right hand side and plugs into a valve in the chest of my drysuit so that I can inflate myself - this is the way I control my buoyancy. The fourth hose comes over the left hand shoulder and is meant to plug into the ABLJ which is a large, heavy, horrible orange bib thing around my neck which can be inflated like a life jacket. The valve the hose is meant to plug into on the ABLJ leaked because it was broken slightly, so I never plugged it in during a dive anyway. So there was no point in wearing it at all really. And without the thing I suddenly felt free and happy underwater. For the first time I could look down and see my hips and legs and fins on the end of my feet. Nothing was in the way when I grovelled along the floor or peered over ledges. My attitude changed completely: the next dive I did was to 42 metres, ten metres deeper than I had ever been before.

The wreck of the Ronda is quite bizarre. This ship was, so I'm told, washed onto a small island during a big storm and was balanced on top of it. When the dismantlers came to work on it they removed too much metal from one side and not enough from the other, so it overbalanced and slid down the slope into the sea where it rests at an angle of about sixty degrees to the horizontal. Simon and I swam down to nearly the bottom, and then came back up along the deck going through a few tunnels on the way. A whole crowd of us pretended to decompress on the rudder which was disguised as a rectangular encrustation of sea growth.

We surfaced in the middle of an appalling squall of hissing rain and hail stones. I left most of my diving gear on so I hardly noticed it as it pelted against the glass of my mask.

In the afternoon we dived a particularly good wreck called the Hispania. It would have been better if Damian hadn't been trying to make me do a dive leadership assessment test, where he is supposed to pretend to be a novice and I pretend to lead him. The conditions were hard as far as I was concerned; there was a current which you had to haul yourself against to get down the line. Once on the wreck you had to grab the nearest rail with your hands and let your body dangle horizontally in the current. We rushed to enter one of the holds of the ship for some shelter. All this time I am trying to pretend to take care of Damian, who is probably actually looking after me. We procceded through some fairly recognisable ship architecture (such as doorways and sheltered walkways) to the bridge where there was a broken bath tub still as white as a urinal. On the way back we had to dash across the open deck a couple of times and avoid being washed away.

Damian made a few corrections to my diving style after we got out. He made me lose four pounds of lead from my weight belt and mount the tank higher up my back. The next time I dived it was a revelation, suddenly being horizontal and able to hover. It was like discovering after two caving expeditions that you'd set the footloops in your SRT gear to the wrong length all this time.

Back out on land the Scottish midges were out in force and ate us for dinner before we could have our own. How can such microscopic bugs carry jaws big enough to bite with such pain? And why does a species with such a ravenous appetite for human flesh inhabit only obscure parts of Scotland where there are hardly any people? Why don't they all piss off to London for the summer where there are loads of people worth eating? I am sure no one who believes in the theory of evolution has a satisfactory answer to this one.

Georgina, Jez and I got away from the midges for half an hour by going shore diving from the campsite. We stumbled across the rocks with so much gear on we were in serious danger of falling over on the way. Diving gear feels just dreadful when you put it all on. It's hot, it's very heavy. You put a thick 8mm neoprene hood on your head to insulate you from the world and make you deaf. And then put on a mask which seals off your nose so you can't breath through it. I usually doubt that I can put up with it for more than three minutes, let alone the whole half hour of a normal dive. But then, when you slump into the water, even if it is only six inches deep, the whole lot sinks in together. It suddenly feels natural and even nice.

I pottered along after Jez and Georgina and joined in the seaweed fight they started to have. I tried to do a somersault and collided with the ground. It was impossible to collect any shells since every single one contained a hermit crab and walked around. At one point Jez unwrapped and shared a Twix chocolate bar with us. It was not very nice. You got half a mouthful of salt water when you took a bite and it was impossible to chew and have the regulator in your mouth at the same time. Jez picked up an obesely large scorpion fish which was mostly head and nothing much else. We passed it around and I thought that it might be sick or something until it seized its moment to get free and sped away into the distance.

The next day I dived on two wrecks with JL. The first was called the Shuna which was a coal carrier. The cargo holds are full of coal so you can't go down into them, but you can go down the funnel and also into the engine room. JL said that the heap we saw there was a reciprocating steam engine. He understands and knows a lot about ships, or bullshits when it's safe, or both. This was a relatively newly discovered wreck. The people who discovered it kept it quiet for several months until they had chiselled off and recovered everything they could move. Any equipment that might have been in the rooms before, and even all the brass port hole frames around the port holes were gone. At the back end of the ship the propeller was still there. This is the first time I have ever seen a propeller. Large as it was, I don't expect it to be there for long. You can tell which are the divers on any caving trip: they are the ones bringing out the stalactites in their pockets.

The Thesis in the afternoon was probably the most beautiful wreck of the lot. All the panels of the hull had rotted away leaving behind a complete skeleton that was rich with fluffy white dead man's fingers. The sunlight was bright for a change and made the place almost sparkle like the inside of a greenhouse, but without the humidity. We swam in circles chasing each other's fins in the confined spaces defined by the lattice work. The gaps were only wide enough in a few places to get through. In spite of my poor posing ability, JL took some extra good photos of me that I am going to make large copies of and put on my wall to bring back memories.

That evening we drove to the pub in Lochaline. As usual I could only manage a couple of bitter shandies. Diving takes it out of me so much that it's the all my body can put up with. Jez and Georgina went outside for a walk. Damian was pleased to see this because he was in favour of there being a chance of romance between them two. Then he saw Andy rush out the door and join them. Damian thought Andy was the greatest gooseberry ever. Although I am in favour of gooseberrying at all times because (a) it never can affect me, and (b) being a gooseberry myself is the closest I tangibly ever get to any kind of romance, I could see it was futile because the two of them shared a tent together and cooked together on every single night of the trip.

Allowing my mind to dwell on this subject got me depressed as it usually does. Damian told me that all I needed to do to have a woman was shave off my beard and get a suit. But he was unable to explain or elaborate on this bizarre statement at all. When probed with further questions it turned out that none of his previous girifriends had any connection with suit wearing, so he was obviously bullshitting; no one has ever talked sense to me on this subject and I usually find that the best solution is to line up a few beers and drink them. But I couldn't do that that evening.

I went out for a walk on my own down to the end of Lochaline pier and looked over the side. The water was dark. It goes down to at least ninety metres here. This was where last dive of the trip was scheduled to be. I tried not to think about it too much, given that I am quite afraid of depth. I broke a piece of wood off one of the posts and dropped it in, and waited several minutes for it to resurface. It didn't. I took it as a bad omen. Oh well, I thought to myself, at least I get one good dive in the morning before I die.

The last boat dive was on the Hispania again because it was so good. Damian led me through it. In the engine room we peered down the sides into other rooms which contained masses of junked machinery. The wreckage was spooky as it lay twisted and gathering silt in the darkness. We went through a tortuous swim-through which came out near the bridge. Then, because there was no current, we could swim along the sea floor to the bows. We peeped our heads over the railings and surprised Georgina and Andy who were standing in front of the bridge. The ship was so intact and recognisable you felt it was wrong to swim across the decks and that you had to walk.

We struck camp and headed for Lochaline ieer. My stomach in my throat and my mind went into panic over-ride mode. We still dived in two waves, but came to the agreement that divers from the first wave should not let those on the second wave know the maximum depths before they went in. Damian wanted to jump in off the pier with me and I agreed because I thought I might as well go out with a bang. I'd heard some bullshit about the badness of jumping from a great height with fins on in that it can bust ankles, but ignored it. A total of about fifteen stone of me plus equipment hit the water like bomb and didn't feel a thing. Thick neoprene is such good padding.

We stuck our feet in the air and embarked on an express elevator to hell. At twenty-eight metres I began to feel narkey. At thirty-five the world was beginning to become two dimensional. Jez, on his dive, made gestures of pretending to smoke a joint. At forty metres Damian grabbed hold of my wrist and hid my diving computer from me. We went further down and I can't say there was much left of me when we began to go up. At forty five metres Damian let go of me and went back down. I shone my torch at him till he was out of sight. Slowly, I thought to myself: If he thinks I am going to hang around here waiting for him and not expect me to piss off in a general upward direction, he must stupider than I thought. I swam up a bit and pottered around for a while looking for crabs and other signs of life in the cracks. Then I looked at my computer. I was still thirty eight metres below the surface and all by myself. My maximum depth had been 50.1 metres. If I didn't start going up really soon, my computer said, I would need to make decompression stops on the way. At twenty metres I found the piece of wood I had thrown in the water the night before perched on a ledge.

It's not a bad idea to make decompression stops anyway, even when the calculations say you don't need them. The calculations are not foolproof and you only have one body to ruin with the bends. I faffed around between six and ten metres among the wooden pillars of the pier for about ten minutes on my own, and then Damian found me. Was he glad to see me or what? He had been looking everywhere for me and felt so guilty at abandoning me when he went back down to obtain his depth record (he got 64.5 metres, but JL made it to 66.6; all the rest of us scored over 50). He explained later that he had grabbed my computer to stop me from being freaked out by the depth.

We packed up the boats and our things and had an ice cream before heading off to Glen Coe. According to an article we read in a magazine, there is a divable river at a place called Glen Etive, very close by. The road down this glen runs beside a not very convincing standard Scottish stream. This stream eventually opens out into loch Etive which runs out under Connell Bridge near Oban. Somewhere before that it enters a gorge and becomes very deep. Jamie and I ran down from the road to look at it From the bridge the water looked like black ink between the rocks even in sunlight.

We camped and dived in it shortly after eight in the morning, all seven of us at once (not Simon who doesn't like strange dives). Underneath, the water was absolutely clear, but tinted brown with peat. Much of it was four or five metres deep. When you turned on your back and looked up you could see suds swirling about on the surface and it was like staring up from the bottom of a glass of good beer that has gone flat. Down at the deepest point under the bridge it was ten metres and dark. Against my better judgement I did not take a photograph of the dead and bloated sheep that was lying in a corner there. We fought our way upstream, hand over hand against the current where the gorge was narrow until I came unstuck and collided with everyone as I flew past.

Eleven hours of driving later and one hour of frantic cleaning and packing up at the stores left me as a half dead wreck at ten pm on Henri and Dave's doorstep in Bristol. I crawled inside and got fed dinner. It took the whole of the next day to come to terms with the rest of the world again before I could go back to my job in sunny Cambridge.