From the World Heritage inscription:
The site comprises 244 islands, islets and coastal areas located in the Gulf of California in north-eastern Mexico. The Sea of Cortez and its islands have been called a natural laboratory for the investigation of speciation. Moreover, almost all major oceanographic processes occurring in the planet’s oceans are present in the property, giving it extraordinary importance for study. The site is one of striking natural beauty in a dramatic setting formed by rugged islands with high cliffs and sandy beaches, which contrast with the brilliant reflection from the desert and the surrounding turquoise waters. The site is home to 695 vascular plant species, more than in any marine and insular property on the World Heritage List. Equally exceptional is the number of fish species: 891, 90 of them endemic. The site, moreover, contains 39% of the world’s total number of species of marine mammals and a third of the world’s marine cetacean species.
The property ranks higher than other marine and insular World Heritage sites as it represents a unique example in which, in a very short distance, there are simultaneously ‘bridge islands’ (populated by land in ocean level decline during glaciations) and oceanic islands (populated by sea and air). Moreover, almost all major oceanographic processes are present, of extraordinary importance for the study of marine and coastal processes. These processes are indeed supporting the high marine productivity and biodiversity richness that characterize the Gulf of California. The diversity and abundance of marine life associated with spectacular submarine forms and high water transparency makes this a diver’s paradise.
In August 2011 I visited the island of Espiritu Santo near La Paz, Mexico. We went out via boat and saw an abundance of marine life including sea lions, dolphins and sea turtles. The arid islands offered a sharp contrast to the deep blue waters of the Gulf of California. It was a great experience and one that I would do again in a heartbeat.
View my complete list of UNESCO World Heritage sites.