Even without the mild nausea brought on by the bouncing sea beneath me, the delicacy on offer would not look enticing. Adventure guide Paul Bramble has just pulled a limpet from a rock, dug out its flesh with his finger and is holding it out towards me. The rigid yellow disc has a soft grey depression in its middle and reminds me of a tiny rolled-up condom, although I keep this thought to myself in front of eight-year-old Arthur, my son and co-explorer on this paddle-and-forage adventure.

"What's it like? Can I try it?" Arthur pleads from the plastic kayak bobbing around next to Bramble's in an inlet on the north Pembrokeshire coast. "They're better when they're cooked," our guide warns, but not before I've bitten off enough of the rubbery flesh to know that no amount of wine, garlic or parsley could redeem it.

By way of a palate cleanser, Bramble scoops his hand through the water and produces a handful of sea lettuce. The chef turned adventurer explains how he uses this satiny vegetable to add a taste of the sea to noodle broths and risottos. "There's no seaweed you can't eat," he reassures, inviting Arthur to taste a wrinkly ribbon of translucent brown laver. "You can have this for your breakfast," he continues. "Just rinse it, boil it and bung it in a liquidiser."

It is because we are about halfway through our afternoon potter around the north side of Dinas Head that I feel relaxed enough to rest my paddle across the bow and nibble on bladderwrack, thongweed and kelp. One hour ago, as I watched my first-born venture out into a choppy sea at high tide, I was not nearly so relaxed. "Oh, so he's got a whole boat to himself?" I asked, trying to affect the breezy nonchalance of the sort of person I imagine takes their children regularly on yachts or up cliff faces. Two minutes in, it became obvious that Arthur's delicate paddling action was no match for the easterly threatening to blow him to Ireland. Bramble clipped a towline on to his kayak and my heartbeat slowed from extreme panic to mild unsettlement.

So now I can enjoy the gull's-eye view that makes travelling by kayak the best way to see Pembrokeshire's technicolour coastline. Sapphire sea slaps against rocks spattered with lichens and pincushions of pink thrift. I look up at the walkers on the coast path above us and revel in what they cannot see, an architectural underworld of chasms and crevices whose layered rocks contain so many different browns, greys and ochres that they look like oils on a canvas.

Bramble and Arthur have floated over to a blowhole beneath the rocks. My son screams with laughter as the half-flooded cave swallows a wave and then burps it back all over them. I loiter a few feet away, watching a group of daredevil guillemots nesting in the cliff wall. Plopping, penguin-like, from their holes, they fall towards the sea, spreading their wings just inches from the surface. Arthur meanwhile, is enjoying a wildlife education of his own. "Do you want to know something amazing about barnacles?" Bramble asks him. "Their willies are 10 centimetres long."

This line must have gone down a treat with the school groups that Bramble worked with before co-founding Dragon Activity Guides with friend Alun Lewis earlier this year. Pairing his twin passions of cooking and coastal adventure, he specialises in tailor-made outings that combine kayaking, surfing, climbing and/or coasteering with homemade picnics and turf-and-surf barbecues. Kayakers get to catch their own supper, which is why I'm wiggling a fishing line over the side of my boat when Bramble announces that the tide is turning: "We'd better head back or we'll get pulled around the headland."

After 10 minutes of furious paddling (not for Arthur, who has given up all pretence of effort), we stop next to a yellow buoy; Bramble hefts out a heavy, seaweed-laced lobster pot to reveal a magnificent brown crab. "Mind its claws," he warns as he shows Arthur how to hold it safely. "One squeeze and he'll have your finger off."

We swim in the little bay of Cwm-yr-Eglwys while Bramble lights the barbecue and lays out his wares: fragrant homemade bread, fresh salads and a cool-box full of bangers and chops from his local butcher. There's also the back-up beast: a half-metre-long lobster retrieved from one of yesterday's pots. The warm, pillowy flesh that Arthur coaxes out of its claw with the wrong end of his fork is, he declares, the best "fish" he's ever eaten. "Don't get used to it," I tut, sharing my last morsel. Then again: "Maybe we should get a kayak."

• 01348 841336, dragonactivityguides.co.uk. A half-day kayak-and-forage adventure with beach barbecue costs £50 for adults and £25 for children