Geoheritage in the Shallow Submarine Slopes of an Oceanic Volcanic Edifice: A New Option for Diving Geotourism

Abstract

Volcanic oceanic islands are large buildings that grow from the ocean floor up to their highest peaks above sea level. It is estimated that only a small part of the volcanic edifices emerge above sea level, leaving almost 90% of the volcanic structure submerged. The geology of this submerged area is mainly known from indirect geophysical studies, general and detail mapping, bathymetry, and some drill holes and different types of dredges and humanned--unhumanned submersibles. However, this information is quite poor for geoheritage studies since it does not allow a geological classification of the environment, their genesis and geoheritage value. Hence, direct observation in inner platform and coastal zones has become essential to identify submerged geological structures, rocks, sediments, pyroclastic deposits and morphologies that could be considered as part of a geoheritage inventory. In fact, underwater there are unique and representative geological elements, which in many cases are visited by divers who do not know their significance and value, since their main objective is to observe the fauna and submarine scenery. Therefore, the identification and enhancement of underwater shallow geological heritage is crucial for the development of one of the emerging resources, underwater and diving geotourism. This study contributes to the knowledge of the shallow submarine geology of Lanzarote and Chinijo Islands UNESCO Global Geopark and highlights the existence of fifteen geosites suitable for the implementation of sustainable submarine geotourism.