Jane Knight and her son walk a slippery plank, go underwater astronaut training, visit a drive-in volcano and more in an action-packed week on this Caribbean island.

Three wedding parties are staying at St Lucia’s Windjammer Landing Villa Beach Resort at the same time as my 10-year-old son, Christian, and me. It’s not surprising; the island is ridiculously romantic, with its snaggle-toothed volcanic mountains, the Pitons, rising out of an azure blue sea. Small wonder, then, that the tourist board folk have been so successful in marketing this little Caribbean bolthole with its many adults-only hotels as the ideal retreat for couples.The thing is, we only hear about the weddings from the staff – we don’t get a single whiff of any of them, or a glance at a Bridezilla. Why would we, when we’re having so much fun enjoying the free watersports, trying to walk a slippy circular plank on a giant inflatable out at sea, and watching fire-eaters and limbo dancers after a delicious dinner down by the beach?

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St Lucia's lush hills and turquoise seas

This 60-acre hillside hotel in the north of the island may be the epitome of elegance but, like a handful of other resorts, it is actively courting the family market. As well as some great deals during the summer months – typically the Caribbean’s low season – they have kids’ clubs, child-friendly menus and enough to keep the family occupied for the whole holiday without ever needing to step outside the resort.But step outside you must to truly appreciate everything St Lucia has to offer, and to understand why this little island is a million miles away from your usual Caribbean fly-and-flop. During a week on St Lucia, my son and I squeezed the most fun we’ve ever had into a single holiday.We bounced on the seabed in special diving helmets that made us walk like astronauts, collapsed in fits of laughter as we negotiated a Total Wipeout-style water obstacle course, then whooped and whizzed through the forest on a zipline course.

There was more, too, after we transferred to Sugar Beach, a Viceroy Resort in the south (though the island is small, its roads are tortuous and busy, so it’s best to divide your stay between two hotels if you can). Here, we drove into the crater of an active volcano where people bathed in hot springs and slathered themselves in mud, then ventured up the hill to a cacao plantation to make our own bar of chocolate and feast on a chocolate-themed lunch.The heavens opened as we toured the plantation (there’s a reason this island is so fecund, with rainforest crawling up the hilly interior; you will get wet, whenever you go). But nobody cared – it was still hot, and there were umbrellas at the ready. By the time our chocolate bars were set, the sun was out again, illuminating those lovely Pitons. Below is our guide to the best activities on the island.

Best things to do in the North:

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Bouncing, laughing and playing at Splash Island

Splash Island

They call Splash Island a waterpark, but don’t expect slides and rides – it’s more a collection of giant inflatables at sea, just off the Bay Gardens Beach Resort & Spa at Rodney Bay. We spent a happy hour clambering up cliffs, falling off trapezes and trying to run across a line of floating rubber ‘water lilies’ before we slipped and plunged into the water. We laughed, fell in, were hoiked up by the lifeguards, then laughed and fell some more. ‘I could have done that all day,’ was my son’s verdict. My arm muscles couldn’t have, though.

Price: £40pp for half a day, with lunch

Find out more about Bay Garden Resorts

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Preparing to go 'space walking' on an underwater sea trek

Sea Trek

Why dive when you can experience zero gravity underwater on a ‘space walk’ in Pigeon Island National Park? Under the expert guidance of Angel, my son and I donned space-style helmets and bounced along the seabed 20ft below the surface (this is actually how astronauts train). There isn’t much coral or fish, but it’s a great experience; we couldn’t stop grinning with delight at each other as we hopped, skipped and jumped, breathing air pumped via a tube.

Price: From £67pp. Minimum age is five, but it’s better if they’re older; my 10-year-old found the helmet quite heavy before being submerged

We’ve had some interesting experiences ziplining around the world, so it was good to see we were with Rainforest Adventures, the same company we’d used in Costa Rica. They are very safety-conscious, with ‘brakes’ at the end of their eight wires, so you don’t have to touch the cable yourself, or risk smacking into a tree. That said, this is more ziplining for beginners, with wires not as fast or stretching as far as other courses we’ve done. Other companies operate in the south of the island.

Price: From £75pp, including transfers from the hotel

Best things to do in the South:

Chocolate-making

Who can resist playing at Willy Wonka and making their own chocolate bar? At the old Rabot Estate cocoa plantation near Soufrière, families can join a fun tree-to- bean and bean-to-bar experience. After learning it takes two large cocoa pods to make a bar, and wrinkling our noses at the smell of fermenting cacao beans, we grafted our own mini cacao tree. Then it was time for business: making our own bars, with a lot of tasting along the way.

Price: The Hotel Chocolat tree-to-bar experience runs from Monday to Friday and costs £63pp. A two-course lunch costs about £30.

Find out more about Hotel Chocolat

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Hold your nose: the world's only drive-in volcano smells of rotten eggs

Drive-In Volcano

When they talk about the Caribbean’s only ‘drive-in volcano’ in St Lucia, they mean it. At Sulphur Springs, you actually motor into the 4km diameter collapsed volcanic crater. It’s a strange moonscape, with pools of boiling water, where gases formed in a magma chamber 8km below the surface belch to the surface. Now, a small community of about 100 people live there, and goats roam freely (they love the bad-egg smell). After your tour, you can wallow in the hot springs and coat yourself in mud for some interesting snaps.

Price: Admission costs from £6pp, with a tour and bath

Find out more about Soufriere Foundation

Nature Trails

Instead of the hard hike up Gros Piton, we opted for a much gentler nature trail nearby, stopping periodically to learn about plants. The real reason for doing this, though, is that it gives you exceptional views of the Pitons – and the obligatory staged photos of us hugging them and licking them.

Price: £7pp, though you’ll need extra to tip the excellent guides

Find out more about Tet Paul Nature Trail

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A grand luxury villa at Sugar Beach

The Lowdown: St Lucia

Where to stay

St Lucia might be only 27 miles by 14, but getting anywhere on its windy roads takes time. If you can, it’s worth staying at two hotels, in the north and in the south; we mixed the elegant Sugar Beach, a Viceroy Resort, with Windjammer Landing Villa Beach Resort.

Sugar Beach, a Viceroy Resort, Sugar Bay

If you can afford it, this is the place to come, for both the stunning views of the Pitons and an upmarket family experience. Tuk-tuks ferry you from your private villa with pool and butler service to the main pool, the beach, kids’ club, the rainforest spa and the various restaurants. It’s the perfect combination of elegance and family-friendly, and you can book it on an all-inclusive basis. A week in May half-term costs from £7,829 per family of four sharing a Superior Luxury Cottage on a room only basis, with flights and private transfers, with ITC Luxury Travel. This price is £4,586 less than in February half-term.

Windjammer Landing Villa Beach Resort, Labrelotte Bay

What’s not to like about an imaginative kids’ club that has activities such as egg-throwing, along with motorised watersports in the all-inclusive rate, and great evening entertainment. Oh, and there’s good food and an excellent spa. Note, though, that the pretty plantation-style villas here cling to the steep hillside, which means you’ll need to rely on the (slow) shuttle bus. Tropical Sky has seven nights in July and August from £1,399 per adult and £999 per child, room only, with flights. This is a saving of up to £380pp.

Bay Gardens Beach Resort & Spa, Rodney Bay

Save £500 per family at the Bay Gardens Resort, bang on the beach and home to the Splash Island inflatables course. Destinology offers one week between 1 June and 15 September from £1,349 per adult and from £935 per child sharing their parents’ room, with breakfast. The price includes flights and private transfers, with Destinology.

Find out more about St Lucia.

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