The first thing that strikes a visitor on arriving on Sweden's north-west coast is the odd-looking but appealing landscape. Masses of granite forms high cliffs, low skerries and vast islands but, unlike most of Britain's rocky coastlines, these stone formations give the impression of being as soft and shapely as, well, one of those Swedish girls.

The coloration goes from eternal grey to a warm pink. Very little grows on most of the islands, leaving a pure and almost poetic meeting between stone and sea. Put all this together and you have a unique and beautiful archipelago.

The sea surrounding the area is called the Skagerak and is well fed with nutrious salty water from the North Sea. This gives the area the same kind of contrasts that you find in Egypt. On land the raw nature seems lifeless and unforgiving, whether it is Egypt's desert or Sweden's bare granite, but under water you are overwhelmed by a variety of creatures occupying every nook and cranny.

Last summer and autumn I spent time diving and getting to know the area. On a marvellous day in late July I was standing aboard a former navy vessel converted into a dive boat, cruising at 30-plus knots with the wind in my hair and the scent of sun and sea in my nostrils. The glittering waves were dotted with sailing boats, and on a small rock seals relaxed in the heat, happily unaware of the plague threatening them.

We were holidaying in the Kungshamn area in central Bohüslan. This is my favourite part of the north-western coast, combining good diving with a picturesque fishing village that offers impressive night life during the summer. But you can find lovely places all along the coast, from Gothenburg in the south to Stršmstad, close to the Norwegian border, in the north.

The Gullmaren fjord, close to the town of Lysekil, is an area apart. The only true marine fjord in Sweden, it offers a different form of diving, with very deep and steep walls plunging to a soft bottom. This is where I was on that July day.

At the dive site the blonde divemaster Tessan (who drove a mean chopper to work) briefed us and pointed out the most interesting areas. Diving here is not that difficult, as there is almost no tidal water and the currents are mostly weak. Visibility normally reaches 5-15m, with 20-30m not uncommon on good days.

This was a good day and we quickly slipped into the green, welcoming water. A bubble check at 10m, a change of setpoints on our Inspirations and down we went. Across a small plateau we found the impressive rock wall, thickly layered with life-forms. Large plumose anemones swayed, whitish featherdusters hunted for morsels and dead men's fingers clawed in the weak current, though not for food, as their polyps were retracted.

Inside the many crevices, eyes glimmered back at me as I shone my torch. Small squat lobsters hid their shiny red and blue costumes as best they could, while the abundant and often very large edible crabs stared back in their own stubborn way, unwilling to move for such a silly thing as a diver. Looking carefully in between them, we saw a surprising number of small nudibranchs.

Starfish of many varieties strolled around, comparatively fast-moving alongside their cousins the sea urchins. The bigger red sunstars were particularly abundant. The local ballan wrasse made a few passes to check out the new guests in their neighbourhood, and now and then we could see the silvery flashes of cod out in the green.

As we went deeper, the anemones and dead men's fingers slowly disappeared, to be replaced by plentiful cup corals and scarce and fragile red horn corals. OK, they're not much to brag about compared to the Red Sea's organisms, but it is pleasant to be able to enjoy hard corals this far north.

Reaching the gravel bottom, I took a good look around. The manager of the dive centre had told me a story of two divers who had chanced upon a crate of 18th century Chinese pottery in this area. I would find nothing of that sort, but the idea was still thrilling.

Then I experienced the creepy sensation of being watched, took another good look round and spotted a big crack in the base of the wall. Peeping in, my eyes settled on the biggest lobster I had ever seen! The enormous beast was so old that its shell had turned dark blue, covered with apparent centuries of barnacle growth. I realised that I was trespassing and slowly retreated. It didn't look amused.

As we moved on along the base of the wall, the not-so-little brother of the blue guy came charging along, cavalry-style. This critter was in a more playful mood and stopped to eyeball me at close quarters. Hakan the photographer loved it and fired his ridiculously expensive German flashes repeatedly, aiming the shiny globe of his Nikonos at me and my newfound pal.

Life must go on, however, and our dives as well. We had to avoid aggravating the boat crew by staying down too long, courtesy of our rebreathers. Ascending to the 5-10m shallows, we stopped again to enjoy the show.

We were soundless, so this fishy little city soon returned to its normal rush-hour pulse, the ever-present goldsinny wrasse buzzing around like housesparrows in a playground.

Sit around long enough and there would always be one brave enough to go up front and shine a toothy smile in your face.

Hakan pointed down just in front of me and hey, what do we have here? A big, lazy-looking flounder giving me the evil eye. It was time to head back to the surface.