Present-day volcano imaging and monitoring relies primarily on ground surface and satellite remote sensing observations. The overall understanding of the volcanic edifice and its dynamics is thus limited by surface investigation, spatial resolution and penetration depth of the ground methods, but also by human and material resources, and harsh environments. Here, we show for the first time that an airborne electromagnetic survey provides a 3D global resistivity model of an active volcano. The high-Present-day volcano imaging and monitoring relies primarily on ground surface and satellite remote sensing observations. The overall understanding of the volcanic edifice and its dynamics is thus limited by surface investigation, spatial resolution and penetration depth of the ground methods, but also by human and material resources, and harsh environments. Here, we show for the first time that an airborne electromagnetic survey provides a 3D global resistivity model of an active volcano. The high-resolution survey acquired at the Piton de la Fournaise volcano on La Réunion Island, Indian Ocean, shows unprecedented details of the internal structure of the edifice, highlighting the upwelling hydrothermal system below the craters, magma intrusion pathways and inherited faults. Together with surface monitoring, such airborne imagery have a high potential to better characterize volcano internal structure and magmatic processes, and therefore to better anticipate catastrophic events such as phreato-magmatic eruptions or volcano destabilizations.survey acquired at the Piton de la Fournaise volcano on La Réunion Island, Indian Ocean, shows unprecedented details of the internal structure of the edifice, highlighting the upwelling hydrothermal system below the craters, magma intrusion pathways and inherited faults. Together with surface monitoring, such airborne imagery have a high potential to better characterize volcano internal structure and magmatic processes, and therefore to better anticipate catastrophic events such as phreato-magmatic eruptions or volcano destabilizations. Structures of active volcanoes result from many successive constructive and destructive processes that are interconnected 1-3. Understanding their internal structure is a priority issue to monitor volcanic activity and anticipate catastrophic events such as phreatic to phreato-magmatic explosions, edifice collapses or flank destabilizations. Volcano edifices grow from both exogeneous and endogeneous processes through accumulation of lava flows, explosive deposits and magmatic intrusions. Successive magma intrusions and magma storages at depth generate accumulated deformations and mechanical stresses that weaken the volcano edifice stability, together with structures inherited from previous destructive events 1,4. Water circulation also contributes to the overall complexity and instability of volcanoes. Heating of the water table by magma injections and accumulations at depth generates extensive hydrothermal systems underneath active volcanoes 5. The induced circulation of acid hydrothermal fluids leads to intense leaching and alteration 6. All these internal processes promote surface rupture 7 and significant edifice spreading 8 that can cause catastrophic flank destabilization 9. Imaging the interior of active volcanoes is thus fundamental to determine their internal structure, the dynamic of their magmatic and hydrothermal systems , their potential points of failure and their associated volcano hazards such as phreatic/phreato-magmatic eruptions 10 , large-scale deformation 11,12 and flank instabilities 2,13. For decades, geophysical techniques have been developed and applied to study both the internal structure and the dynamics of active volcanoes. Among others, ground resistivity imagery techniques, such as 2D or 3D electrical resistivity tomography (ERT) 10,14,15 , magnetotellurics (MT) and transient electromagnetic soundings (TDEM) 16,17 , are renowned for being well-suited and reliable in such settings. While ERT oftenly provides high resolution imagery of the first hundred meters 18,19 , MT and TDEM provide a smoother image of the bulk resis-tivity up to few kilometres depth 20. All these methods have been improved during the last decades to image