Vallée de Mai was designated a World Heritage Site by UNESCO in 1983 as an outstanding example of low- and intermediate-altitude palm forest characteristic of the Seychelles.
The site is classed under category IV (Habitat/Management Area) of the IUCN Management Category and designated as a Natural World Heritage Site for fulfilling the criteria i, ii, iii and iv.
These criteria are as followed:
Criterion i: The property is an outstanding example of a major stage in the evolutionary history of Earth in that its ecology is dominated by endemic palms. It is a palm forest preserved in something like its primeval state, dominated by the famous and unique Lodoicea maldivica (Coco de Mer). The population is substantial and, with continued protection, is self-sustaining.
Criterion ii: The habitats provide a refuge that harbours viable populations of endemic species of flora and fauna, providing outstanding examples of significant on-going ecological and biological processes in the evolution and development of terrestrial and freshwater ecosystems and communities. An example is the unique association between endemic geckos and the male inflorescences of the Coco de Mer.
Criterion iii: An area of exceptional natural beauty where a concentration of diverse and unique plant and animal species thrive. The lush vegetation that largely features the Coco de Mer palm produces the largest seeds of the Plant Kingdom. The juvenile leaves of the Coco de Mer are also strikingly beautiful and amongst the largest leaves of any living plant.
Criterion iv: The area is rich in biodiversity and the habitat of rare and endangered species of flora and fauna. The region is the type locality and world’s stronghold for the Lodoicea maldivica (Coco de Mer), Coracopsis nigra barklyi (Seychelles Black Parrot) and the Pachypanchax playfairi (endemic freshwater fish) in particular. With many other endemic plant and animal species, the area represents a remarkable concentration of outstanding natural wealth of the highest importance to science and conservation.