In Dominica’s small capital, Roseau, with its wooden buildings of decaying beauty, crowds line the broken pavements. Trucks drive slowly past while calypso blares from speakers. Each vehicle carries a young woman, waving regally at the smiling crowd. “Miss National Pest and Termite Control Unit”, says the sash across the bust of one young princess.

All over the Caribbean, carnival queens are an institution and Dominica is no exception. Many businesses and government departments sponsor a favourite daughter.

Carnival queens aside, in most other ways, Dominica is different from the rest of the Caribbean. Geologically, it is the youngest island in the region, and while the other islands have been eaten away by time and are now fairly barren, surrounded by icing-sugar beaches, the “Nature Island” is lush with a thousand different plant species. It is still bubbling in the kitchen, a high-peaked, jungle-covered confection with waterfalls and just a few beaches of volcanic shades.

Dominica is almost literally Eden: the man who translated the book of Genesis into English for the King James Bible visited the island in 1593. Historians and biblical scholars think he let his experiences colour his translation. His Dominica journal entries are remarkably similar to some of the Old Testament’s description of the Garden.

Culturally, it is an old-fashioned island. Most visitors are from other Caribbean nations and come to experience what the friendly islanders describe as “the Caribbean how it used to be”.

The day after the carnival parade I am due to hike to the island’s most famous geological phenomenon, Boiling Lake, but my guide is nowhere to be found. When I finally track him down in his village, Laudat, 700m above sea-level, he is in full Rasta outfit. “But I didn’t do my hair mon,” he says, as an excuse. His long afro hair is unkempt. (“I usually do it in tangos”, he tells me later.)

Kelvin Noel, aka Kello, says he is happy to take me on a day’s hike. We will go up and down some 4,000 steps on a 12-mile, six-hour trek through the Morne Trois Pitons National Park, a World Heritage Site. Here, there are various ecosystems, sputtering geysers and sulphurous steam.

We climb the steep steps, cross a river and pass through rainforest and cloud forest. Kello picks a fern that smells of almond, which he uses to flavour hot chocolate.

He tells me stories of witches who, by night, wearing a human hide, fly around in a ball of flame devouring people’s blood. By day, they deposit their skin in a bowl. Because of this, people smear kitchen bowls with chilli and garlic so that the witch’s skin will blister. Hence, old women with boils are witches, and spices protect us from ills.

We see a volcano, Morne Macaque, which erupted 26,000 years ago and is overdue for another. Kello enthuses about the “jack oozee” that we will try out later. He tells me that Dominica is famous for the four Rs: “Rain, rivers, rainbows and romance.”

Next, as if moving from Genesis to Pilgrim’s Progress , we hike down into the Valley of Desolation that has sulphurous fumes belching from the earth. The ground is barren, except for mosses and swirled patterns of ochre, black and red. It is bubbling, hissing and spouting steam and gases. The streams run hot and cold. We do designs on the white mineral layer covering the red rocks as if on a natural Etch-A-Sketch.

Our destination, the Boiling Lake, is less than a hundred metres in diameter. In size, it is more a pond but there’s no quibbling about how it got the other part of its name. Occasionally the steam from the bubbling super-size cauldron wafts over us. The surface of the grey water wells up like a monster coming up for breath. You would cook like a screaming lobster if you fell in.

But the “jack oozee” we visit on our hike back merely simmers. Hot water cascades over the rock pools. I massage my back against the rock, smooth with its mineral-covering, while the iron-rich, blood-tasting water tumbles over me. I climb up a hot waterfall, hauling myself up on roots of an overhanging tree and sit in hot mineral water surrounded by forest. There is no one else around.

Finally, we climb out of the Valley of Desolation and, standing at the edge of the elfin forest, look down on a river with no name while mountain birds whistle. It starts to rain, the wind blows and the view is obscured by cloud.

As a curtain-call, there is just time for a swim in Titou Gorge – a narrow chasm between moss-covered rock walls, shaped like the curving flat buttress roots of rainforest trees. Strange skull-shapes stare at me from the undulating rock. With a bright green fringe of forest foliage arching over the top of the chasm, it is like swimming inside a haunted giant clam, looking up to its fluorescently edged mantle.