Heading out of Scrabster for Ushat Head the cliffs are spectacular. Stacks, caves, cuts and overhanging horizontal ledges. Seabirds everywhere. It holds all the promise of some interesting underwater scenery.
The sea is not particularly big, but very mixed up with waves reflecting from the cliffs and crossing the incoming waves. With six of us now in the boat the low transom and failed bilge pump is worrying, but we decide to dive anyway. At least with divers out of the boat we can drive round and clear the water slopping round our ankles.
Picking a dive site is easy. We just head out from the cliffs guided by the digital chart and watch the echo sounder until we detect an irregular slope at 25 metres. Apparently anywhere along this stretch of coast is good.
Descending past 20 metres I can just pick out enormous square shapes on the seabed below, seemingly arranged in a regular pattern. My eyes and mind say wreckage - could we by some fantastic coincidence have landed right on top of an undiscovered wreck?
The feeling only lasts a few moments as my eyes adjust to the dark green twilight and I see that it is actually huge blocks of stone naturally eroded into these surprisingly regular shapes. Maybe I should be theorising about ruins from an ancient pre ice-age civilisation.
I am diving with Caithness club member Mark Liddiard. We have heard mention of each other for years, various mutual diving acquaintances asking if we are related (we may be very distant cousins), but never actually met.
The current is just mild enough to allow us to meander amongst the blocks without having to drift with an SMB. Everywhere is plastered in huge yellow dead men's fingers. I can't remember when I last saw such a dense and uniform carpet of marine life, especially not on such an unusual relief.
Caithness is the bit of Scotland that sticks out to the north-east, the top end of the Moray Firth, the Pentland Firth, John O Groats, Thurso and Scrabster where the ferry leaves for Orkney. It's the most northerly diving off mainland Britain, some of the most exposed coastline, and in the Pentland Firth some of the strongest currents.
On the other hand, there are two complementary coasts. One facing north and the other facing south-east. The weather has to be extremely unpleasant before there are no sheltered options to dive.
My initial invite to Caithness had come from Caithness club member Davy Carter, to come and sketch one of their local wrecks for a wreck tour. Living at the other end of the country it was a bit of a long way to go for just one dive, so I had grown it into a general diving trip.
A couple of days later we join the Caithness club to dive from Dunbeath, a small fishing harbour facing almost south into the Moray Firth. Only a few hundred metres offshore is the wreck of the Gretafield, a 10,191 ton tanker hit by torpedo in 1940. The Gretafield caught fire, was abandoned at sea, then drifted into the bay before it grounded and broke up.
The wreck now lies well smashed on a rock and sand seabed at 12 metres, though much of the wreckage is shallower. With normally clear water, in the summer this wreck can be literally swamped with kelp. At the end of May when we are diving is pretty much as late in the year as the locals bother.
The shot is right next to an enormous boiler. With the engine right at the stern this turns out to be the most interesting area of the wreck. A total of 6 boilers and the remains of a 4 cylinder steam engine connected by a short length of shaft to the stern.
A more challenging wreck is the Ashbury, a 3,000 ton steamship which ran aground in Togue Bay in 1944. Here we trailer the boat west to a small harbour at Skerray and encounter a slight problem. The slip is sufficiently flat that we need to use a rope on the trailer, but I discover I have lost the key to the ball hitch.
Our solution is to unbolt the tow bar from my car and lower it down the slip with the boat.
In amongst a scattering of rocks and islands the sea is flat and sheltered. We have fun playing James bond with the boat, navigating by the chart plotter and echo sounder as we zoom through narrow channels.
Wreckage is now well distributed along the rocks. Even without the wreck it would be a good dive, there is plenty of colourful marine life beneath overhanging ledges. I have fun sketching it, only coming up after 90 minutes because I had said it would be less than an hour and a half. After a short break and a quick sandwich I am back down to finish my sketch.
Having made my two dives for the day I mind the boat while the others dive a canyon which tunnels right through the end of Eilean Losal. It's a bit of shame that I miss it, but the day is pressing on. Also with a limited reserve of O2 and no convenient local supply I have to ration myself to keep enough for the rest of the trip.
When it comes to cuts and caves, a spectacular location is the Geo of Sclaites. This cut goes 100 metres back into the cliffs at Duncansby head, wide enough to drive the Humber into with room to turn round at the end. Seabirds rest on ledges above us, but all are sufficiently happy with our presence that we don't get dive bombed.
From the back and sides of the geo, narrow caves lead deeper into the cliffs. Marine life is a mixture of kelp, small anemones and tunicates, giving way to sponges and then bare walls as we work further back into the caves. The sea outside is moderate, but with the geo to funnel the waves in and the then the caves funnelling further, there is a powerful surge between the narrow walls.
We finish with a day at Stroma island, selected partly for being sheltered from a strong south-easterly and partly because the slip and John O'Groats is steep enough to launch without having to unbolt my tow bar again!
The remains of the Bettina Danica are well broken up amongst shallow kelp filled gullies, a 1354 ton freighter driven onto the rocks by a storm in 1994. Half the stern is wedged against the cliffs and there are hatch covers perched high on the cliff top.
Underwater the wreckage is sparse, but there are some nice overhangs where the marine life is colourful and not overwhelmed with kelp.
At the opposite end of Stroma we make a shallow drift through a seal colony tucked in behind Swilkie point. This early in the season they are inquisitive, but not in a playful mood.
Next day I drop the boat off at Humber's factory in Hull. While one of the workers is unbolting my tow bar I chat to Frank Roffey about the transom. He shows me a photo of their recent RIB show collection, all with full height transoms and extra long shaft engines. All Humber's hull moulds have been re-engineered to give a transom the same height as the tubes and we had been diving one of the last hulls made with the lower transom. There is also an option to have an open bulkhead across the bow, avoiding the fragile bow locker we had managed to shatter.
Over 10 days diving with 5 or 6 divers, full kit for 2 dives and a mixture of long distance and local boat journeys, the Honda 90 burned £240 of petrol. What we really enjoyed was being able to talk while driving along at full speed without having to shout. One of our divers even went to sleep right next to it, not waking as I started and stopped the engine to keep on station.
The Star M55DSC radio was quite honestly not suitable for use in a RIB. On the other hand we were all thoroughly impressed with the Lowrance LMS240 Echo Sounder/GPS/Chart Plotter. The digital chart modules from Navionics were absolutely brilliant. So good that in areas listed as "uncharted" in the Admiralty catalogue and hence without detail on the digital chart we felt lost without it.