The volcano you can drive into

Saint Lucia's whole southern end is volcanic, part of the same chain of activity that runs down the Eastern Caribbean from Montserrat to Grenada, and the clearest evidence of it sits just outside the town of Soufrière: a collapsed crater full of steaming, sulphurous pools, reachable by road rather than by trail. Local tourism has long marketed it as a "drive-in volcano," on the reasoning that most volcanic craters require a climb to reach and this one can be approached by car almost to its edge. It is, at the very least, an unusually accessible way to stand close to something normally kept at arm's length.

What the springs actually are

The Sulphur Springs are not a crater in active eruption; they are a solfatara, a field of fumaroles and hot mineral pools formed where volcanic gases escape through fractured rock, heated by magma still present well below the surface. The air carries a strong smell of sulphur before the springs come into view, and the ground itself is warm underfoot in places. It is a working demonstration of the same geothermal system responsible for the mineral-rich waters found elsewhere around Soufrière, including at the Diamond Botanical Gardens nearby, where a stream fed by the springs has stained the rock along its banks in shades of ochre and grey, and feeds a waterfall pool that visitors can bathe in.

The peaks above it

The same volcanic system produced the Pitons, the twin peaks of Gros Piton and Petit Piton that rise almost straight from the sea a short distance from the springs. They are not extinct in the geological sense so much as dormant, the eroded remains of lava domes rather than active cones, which is part of why they have taken on their current, near-vertical shape rather than the classic cone profile of an active volcano. Gros Piton can be climbed, with a local guide and a reasonable level of fitness, in a demanding half-day round trip; Petit Piton is a technical climb better left to experienced mountaineers. Most visitors are content to view both from the coast road or from a boat offshore, where the scale of them is easier to take in than it is from directly underneath.

Seeing it as part of a wider week

A land and sea safari built around Soufrière and the Pitons is a standard excursion on Just You's Saint Lucia holidays, based at Rodney Bay in the north but built to take in the volcanic south as a full-day trip. It is one of the more physically active days on offer, involving some walking on uneven, warm ground around the springs, and is worth allowing proper time for rather than treating as a quick stop en route to somewhere else.

For those approaching by sea rather than staying on the island, several cruises calling at Castries offer shore excursions that take in Soufrière and the springs in a more compressed form. The Tropical Horizons: A Caribbean Adventure cruise, a fortnight out of Bridgetown that calls at Saint Lucia alongside Curaçao, Bonaire, Guadeloupe, Dominica, Martinique and Saint Vincent, is one such option, though the time ashore on a cruise day is necessarily shorter than a full excursion from a land-based stay.

A word on the smell, and the heat

None of this is entirely comfortable, and it isn't meant to be. The sulphur smell is genuinely strong, closer to rotten eggs than to anything pleasant, and the springs are hot enough in places that guides keep visitors to marked paths. It is worth going anyway, not despite the discomfort but because of it: there are very few places where a short walk brings you this close to the geology that shaped the island around you, rather than simply reading about it afterwards.