Montagne Pelée, on the French island of Martinique, eastern Caribbean Sea, has been one of the deadliest volcanoes in the world, with 30,000 victims following the 1902 eruption. Thousands of people still live nearby, and this volcano is a strategic “water tank” for Martinique Island, providing 40% of the island’s water supply. Our research takes advantage of a unique high-resolution helicopter-borne geophysical survey conducted over the Montagne Pelée volcano, correlated with geological and hydrogeological data from a boreholes and springs database. Our objective aims to deepen the comprehension of the structure and hydrogeological functioning of this active volcano and to define its hydrogeological conceptual model. The presentation will also demonstrate how electromagnetic data, correlated with hydrogeological data, allowed for the identification of unsaturated zones, aquifers, and seawater intrusions, as well as the main geological units. In addition, data synthesised from pumping tests revealed that the older the unconsolidated pyroclastic deposits, the lower their hydraulic conductivity. This research is a new step toward a better understanding of the Lesser Antilles volcanoes and more broadly of central and proximal parts of andesitic active volcanoes.