Sulphur Springs is currently St Lucia's only volcano and was formed over 410,000 years ago from a weak spot in a large, collapsed volcanic crater. The volcano is dormant with the last eruption being in the 1700s.

St. Lucia is home to the Sulphur Springs Park, which is famously marketed as the "world's only drive-in volcano." Technically, it is located within the Qualibou depression, a 12-square-kilometer caldera formed approximately 32,000 to 39,000 years ago. While it is considered an active volcano, it is in a "dormant" or "quiescent" phase, meaning it has not had a significant magmatic eruption since 1766. Instead of lava flows, the activity is manifested through geothermal features like bubbling mud pools and fumaroles that release steam and sulfurous gases (the distinct "rotten egg" smell). These features indicate that magma still sits relatively close to the surface, heating the groundwater. This geothermal activity is a major tourist draw, where visitors can bathe in warm, mineral-rich mud baths believed to have medicinal properties for the skin. Scientists monitor the area closely for seismic activity or changes in gas emissions, as the volcanic complex remains part of the active tectonic boundary of the Lesser Antilles volcanic arc, which also includes the more volatile Soufrière Hills in Montserrat.