A combined field, GIS and modelling study has given us new insights into the evolution and morphology of Teide stratovolcano in the central part of Tenerife. Central to our analysis was an investigation of the nature and development of a number of enigmatic morphological features, including two large ‘bulges’ at mid-elevation in the north-western and east–north-eastern flanks. This entailed a detailed analysis of high resolution digital elevation data, coupled with new photogeological, geological and geomorphological surveys which were examined using GIS. Our geological investigations reveal that widespread deposits on the steep northern flanks of the edifice were volcaniclastic deposits. These formed during the collapse of incandescent lava flow fronts and, possibly, domes and lobes. Careful examination of other deposits on the lower north-western flank has shown that they formed during magma–water interactions. Detailed analysis has revealed the presence of small coulée eruption vents, abrupt terminations to lava flows and vertical scarps. We were also able to confirm the presence of two nested gräben, along which there has been extensive hydrothermal alteration. Finite element modelling of the basement beneath Teide and structural stability suggest that the Teide edifice was emplaced on the headwall of the Icod island flank collapse. We conclude that the two bulges are flank vents, similar to Pico Viejo, although on a smaller scale. The presence of these flank vents suggests that conduit blockage has probably been more common than previously estimated on Teide. We suggest that future hazard mitigation measures should take into account the potential for large flank vents forming during future eruptions, the possibility of explosive activity from the central edifice, and pyroclastic density currents in front of advancing flows on the flanks of Teide.