Sunken treasures: Exploring rock pools, craggy coastlines and isolated coves ... Anna Pavord recalls how the seaside fired a young gardener's imagination

"A salty column," suggested the editor, "something to fit with our great British seaside special." And, as your gardening correspondent, I should be telling you about griselinia and escallonia, urging the merits of hebe and eucalyptus to stand up to the rigours of seaside life. Instead, I'm thinking of Little Haven in Pembrokeshire, and a rock pool that is coated with something the colour of coral. From a crevice on the side, a small silvery seaweed floats out like Ophelia's hair. I offer my finger to the tentacles of a sea anemone, and it sucks at it, before pulling back into its rust-coloured jelly bag.

At the seaside, I don't want gardens with dogged man-made barricades of saltproof shrubs ("The most effective windbreak is provided by planting two kinds of hedges, a sturdy wind-resister such as blackthorn or euonymus, set in two rows four feet apart on the side facing the sea: then four feet inside that a hedge of hebes or escallonia to filter out what gets past the outer defences ..."). I want the seaside itself: the intricate worlds of the rock pools, with flowerings of mussel shells, each a strange alliance of calm and chaos. We can see the calm. We can only imagine the chaos, as the tide crashes in on the pools, swirling, scouring, tugging at the seaweeds. And then leaving part of itself behind, connecting the microcosms.

All the summers of my childhood were spent at Little Haven, our days marked out by the times and the state of the tides. Were they springs or neaps? Could we climb round to our favourite, most inaccessible beach before lunch, or after? My parents didn't like sitting on beaches and walked clifftops instead, through heather, sea campion and mounds of papery thrift. But they expected my brother and I not to be idiots, so we weren't. The only rule was to be back at base by seven o'clock and we were.

So during the day, we climbed from inlet to inlet, bay to bay, always on dropping tides, rather than rising ones. But honour demanded that we shouldn't make things too easy. Timing was everything. As a wave pulled out from a gulley, you jumped on to a rock that was only temporarily above water. As the sea gathered itself to knock you off, you jumped again, over the divide, landing, you hoped, on a ledge that wasn't too slippery with seaweed.

The scariest thing we ever did was to scramble, climb and swim our way round from Little Haven to the Goultrop Roads. I never saw that name written down - maps existed in our minds, not on paper. So I thought it was called Gold Drop: treasure, mystery and the possibility of locating the leather chest that must exist in the mind of anyone who has ever read Robert Louis Stevenson.

It was a weird place, with scrub oak and tattered sycamore dropping almost vertically from the clifftop to the sea. It was about the only place on this coast sheltered from the southwesterlies and once there had been a lifeboat station here, a sailing lifeboat, with oars for 12. It closed in the 1920s because there were never enough people around to make up a crew. Then a massive cliff fall tore away the fragile track leading down to the shoreline and Goultrop was sealed off - inaccessible, except by sea.

Because it faced north, it was a dark place. The land dropped steep into the sea, which rose and fell with the tides to a barnacle line on the rocks. There was no beach, seemingly no bottom, and the water swirled with brown weed - bladder wrack, saw wrack and long clammy ribbons of oarweed. We dared each other to swim across Goultrop through the seaweed, not a dangerous thing to do, but terrifying if you are cursed with a fertile imagination. The dark woods watched. The dark water waited. The dark weed wrapped itself round us as we pushed through to the far side of the Roads. We did it. But we never did it again.

I've never lost the slight frisson of fear the sea gives me. As a sailor, I respect it; as a gardener, I'd very much prefer do without it, because with a sea view comes a wind, bearing salt on its wings. But seaside gardeners determined to grow what they want, rather than what wants them, might start to plant the dreary windbreaks, the cheerless hedges four feet apart and find within a few years, they've not only lost half the garden to hedge, but also planted out the view.

The seaside places I've liked best are the ones that embrace fully where they are, without trying to change the script. There was a house I went to once, on the north coast of Cornwall, that got it just right. It's always exciting, driving to Cornwall. You have the curious feeling that the edge of the map is looming up in front of you rather fast. At any moment, you expect to hurtle off the narrow pointed toe of the British Isles, next stop America. The chubbiness of Devon gives way to a tougher, gaunter landscape. Instead of trees, there are forests of tall, white windmills, spinning light and heat and microwaved suppers out of the damp Cornish air.

On the very edge of the edge, hanging on to the brink of the cliff was this old wooden house. To find it, you had to take a footpath over the tracks of the St Ives to St Erth railway and plunge down into the lush undergrowth behind Carbis Bay. If you had jumped from the path, you would land astride the wood shingled roof of the house, which was tucked on to a narrow ledge, the only bit of flat ground left before the land tumbled down to the sea. Squeezed between sheaves of montbretia and luxuriant curtains of ivy was a small path leading to the front door.

After the dark tunnel of the approach, you entered a room so bright, so white and so shiny, you blinked like a mole surfacing in Piccadilly. Big windows ahead looked out on to the turquoise water of the bay, framed between the huge trunks of Monterey pines and aged macrocarpas. The floorboards were the colour of sand and the mats were made of sea grass. The light was extraordinary. It was as though you were caught in a bowl of shining air. Not enclosed but floating.

On one side of the sitting room, a deck was slung out to provide a big sitting out space. The guard rails were made from stainless steel yacht stanchions strung at intervals with the kind of twisted wire that boatbuilders use for halyards (they don't get in the way of the view). The deck sailed out over the jungly garden, supported on huge wooden pillars thicker than telegraph poles. Banana palms and tree ferns tickled the joinery underneath. Then the land fell away vertiginously in a mass of bramble and thicket.

What I loved about the deck was the illusion that sitting there, floating above the bamboos and trees, I was about to slip my moorings on land and sail off on a long, long voyage across the turquoise bay. And there wasn't an euonymus or an escallonia in sight.