It’s not every day you get to walk up a volcano, especially an active one. So I am determined that a drop of rain, fog, and gale force winds aren’t going to put the mockers on my hike to the top of La Soufriere, St.Vincent’s highest point. This is the Caribbean after all, where storms come and go faster than rum punches.

Sailor isn’t so sure. He regularly guides holiday makers to the caldera, and knows that sometimes, where a volcano is concerned, things can go wrong.

“I had to carry a man on my back last week,” he says from behind the wheel of his minibus. “It’s damp up there, and he slipped. It took me an hour and half to get him back.”

I assure him I won’t be any trouble, insisting we stop and buy a quart of Mount Gay. If things go awry on the trail, I say, he has my permission to leave me, and the bottle, behind.

St.Vincent is ‘mainland’ among The Grenadines’ 32 islands. Once prosperous from arrowroot, bananas and sugar, with black sand beaches (that don’t fit into many people’s idea of a picture postcard island holiday), it now finds itself on the back-foot, reeling from the global downturn.

What St.Vincent does have, in truckloads, is an incomparable natural world. There are rain forests, huge waterfalls feeding into tropical lagoons. There are nature trails, and botanical gardens, and salt ponds. There’s the Mesopotamia Valley (itself an ancient caldera), known as the breadbasket of St.Vincent, with soil so mineral rich the crops grow themselves, and of course, there is the big daddy of them all, La Soufriere, the 4000 ft volcano, that last erupted in 1902.

St.Vincent is 11 miles wide and 18 miles from north to south. With my hotel, Young Island – 100 yards off shore and very James Bond circa 70s –  and most of the other  hotels clustered around the south coast, close to the airport and capital Kingstown, and nearly all of the headline natural resources in the north, days out need to start early. With the centre of the island mountainous and impenetrable, the fast roads – ie those with the least potholes and jay walking goats – follow the coast.

Sailor and I set off after breakfast. The drive to the trailhead is expected to take 90 minutes from my hotel in the south. From the clearing, with toilets and a cafe four miles inland at 900 ft, it could take up to two hours to hike to the 1.6 km wide caldera, depending on my fitness level. That’s 3000 ft of hiking, the trail steepening the higher it goes.

“I had this guy the other week, he was over 300lbs,” says Sailor. “I looked at him and told him the trail gets tough and I wouldn’t recommend he attempt it. He got cross and insisted. He gave up after 10 minutes. “If you’re not into hiking and steady walking it’s not for you.”

Our drive passes Argyle where the groundwork has been laid for a proposed international airport – if they can raise the capital to complete the job, and a string of black beaches populated by  egrets. There are stalls selling root crops, dasheen, eddoes and yams, and calalou used in soups, and men holding up bags of tiny fish called tritri. Compared to the west coast road, a serpentine track through countless villages, this one is fast. We pass Black Point, one of the locations used in the Pirates of the Caribbean movies, where Sailor’s trips sometimes stop for a picnic.  Minutes later we pull over outside Ferdies Bar, in Georgetown, and while Sailor arranges for our packed lunches I drink a glass of iced Mauby, a dry, taupe coloured infusion made from tree bark. Georgetown was the capital under British rule and the buildings have something of a stout, satanic, 19th century colliery town about them.

Close to the turn off inland Sailor shakes his head. When the wide Rabacca River here is this swollen it’s a sign the volcano trail is impassable. He purses his lips and looks to the darkness of the mountains  directly ahead. This is Carib country, the part of St.Vincent inhabited by South American indians who migrated to the Grenadines nearly 1000 years ago.

The trail turns out to be  tougher than I’d expected. After a mulchy walk along a forested ridge the gradient tightens with flights of slippery wooden steps cut into the side of the volcano. I’ve heard there are dreads up here cultivating marijuana. Right now, already tired, and the caldera shrouded in fog, the last thing I need is to be confronted by a whacked out stoned mountain men with a mistrust of outsiders. Every sound makes me twitch and I’m glad Sailor is with me.

We’ve been walking for 40 minutes, and making good time, when I see three hooded shapes emerging from the mist, each carrying a heavy load. Their heads are down and I can’t see their faces. “I wouldn’t go any further,” says a voice.

It belongs to Robert Watts, an English  volcanologist, based in Trinidad. He and his team had been attempting to install sensors – volcano detectors – in the  river bed, further up the trail. But the weather had proved to much, even for them, and they are turning back.

“Other volcanos let you know in advance when they’re about to go,”says Watts. “But this one – it  might only give a month’s warning.”

The team tarry while Watts explains the difference between volcanos that explode and those that ooze; it all depends on how fast the gas escapes, and without sensors there’s no way of knowing. The next minute they’re gone, leaving Sailor and I to ruminate on what might have been.

We return to the trailhead, with frigate birds circling overhead, and enjoy our lunch from the comfort of the picnic area, La Soufriere drifting in and out of the clouds.