Direct outcrop observation and field data collection are key techniques in research, teaching and outreach activities in volcanic areas. However, very often outcrops are of difficult or inaccessible access, such as in areas with active volcanoes or steep cliffs. Classical remote-sensing surveys by satellites or airplanes are expensive, rarely reach sufficient resolution to allow high quality 3D visualisation of volcanic features, and do not facilitate mapping of vertical cliffs. We describe a novel approach that uses the immersive Virtual Reality (VR) based on real world 3D Digital Outcrop Models (DOMs) from images surveyed by unmanned aerial vehicles (UAV). 3D DOMs are built up using the Structure from Motion (SfM) photogrammetry technique, and a Virtual Reality scene is created using game engine technologies. Immersive real-time exploration of the environment is possible through a head mounted display, e.g. Oculus Rift. Tools embedded in the VR environment allow the user to map polygons, lines, point features, measure orientation, dip, inclination, azimuth, area, thickness and even take virtual photographs. Using three examples of volcanic areas with different geological features, we demonstrate the potential of our approach to allow users to be able to virtually map and measure remotely, and to collect data for research and teaching. Our approach is of paramount importance also for outreach, as it allows non-specialist audiences (e.g. common citizens) to experience and appreciate highly complex volcanic features through customised, hands-on immersive VR tools. Response to Reviewers: I have corrected the paper and figures as suggested by the Editor Taddeucci. Author Comments: As suggested by the Editor Taddeucci, I added three videos related to the paper as Supplementary material, and a pdf containing the video captions (a very brief description).