Abstract: The invention relates to a device (1) for inspecting a cavitation damage or a crack of a runner (7) of a hydro turbine, comprising a remote operated vehicle (20) or an autonomous underwater vehicle, comprising at least one camera and/or scanner, and means (24) for processing images from said camera and/or scanner to generate at least one 3D view and/or IR thermal view of at least a part of a surface, or of a subsurface, of said runner comprising said cavitation damage or crack, said device further comprising means to reconstruct a 3D view by photogrammetry and/or means for locally heating, for example by induction or by a laser or by a heated water jet, said at least one part of a surface of said runner comprising said cavitation or crack.