8 pages, 11 figures.-- Printed version published in issue May-Jun 2008.In 1972 UNESCO created the World Heritage List to 'preserve the world's superb natural and scenic areas and historic sites for the present and future generations of citizens of the entire world'. Nominated sites must be of 'outstanding universal value' and meet at least one of ten selection criteria, six cultural and four natural. Teide National Park (TNP) was inscribed in the World Heritage List in 2007 for its natural beauty and its 'global importance in providing evidence of the geological processes that underpin the evolution of oceanic islands' (Criteria vii and viii). The geological values rendering PNT an exceptional site are analysed in this article. Volcanism in Tenerife and TNP correspond to the Ocean Island Alkali Basalts (OIB), whereas the already nominated (1987) Hawaii Volcanoes National Park, from a different geodynamic setting, belongs to the Tholeiitic series (OIT). Both National Parks complement each other to represent the entire range of products, features and landscapes of oceanic islands. The main geological elements of this Park include Las Cañadas Caldera, one of the most spectacular, best exposed and accessible volcanic calderas on Earth, two active rifts, and two large felsic stratovolcanoes, Teide and Pico Viejo, rising 3718 m above sea level and around 7500 m above the ocean floor, together the third highest volcanic structure in the world after the Mauna Loa and Mauna Kea volcanoes on the island of Hawaii.Peer reviewed