CNRS News takes you on a trip to the foot of Snaefellsjökull, a volcano in Iceland close to the heart not only of French writer Jules Verne but also of the researchers at the Institute of Physics of the 2 Infinities (IP2I) in Lyon (central eastern France). Their goal is to obtain images of the volcano's interior, so as to monitor its dynamics as well as changes in the thickness of its glacier in real time. Our guide is Jacques Marteau, laureate of the CNRS 2022 Innovation Medal, who uses muography, an innovative technique to image the interior of structures.