They counted nearly 700 endemic species, found nowhere else on earth; only New Zealand,[4] Hawaii, New Caledonia, and the Galápagos Islands have more impressive numbers.

The Hajhir Mountains in northwestern Socotra are composed of precambrian granites and metamorphic rock, and include Mashanig, the island's highest point (1,519 m).

Samhah is 50 km southwest of Socotra with an area of 41 km2 and also comprises a limestone plateau reaching 680 metres elevation.

The opening of the East African Rift created the Gulf of Aden and separated the islands from the Arabian Peninsula starting 18 million years ago.

Small mountain streams sustain aquatic habitats, and can flow down through the lowlands during the cooler and wetter winter months and during high rainfall events.

[10] The long geological isolation of the Socotra archipelago and its fierce heat and drought have combined to create a unique and spectacular endemic flora.

[13] Genera endemic to the Socotra archipelago include Angkalanthus, Ballochia, Cephalocrotonopsis, Cyanixia, Duvaliandra, Haya, Lachnocapsa, Paraerva, Socotrella, and Tamridaea.

socotrana, Ziziphus spina-christi, Olea europaea, Balanites aegyptiaca, Cupressus sempervirens, Vachellia tortilis, Salix alba, Juglans regia, Populus alba, Populus nigra, Quercus coccifera, Quercus ilex, Quercus pubescens, Pinus halepensis, Pinus nigra, Pinus pinea, Ceratonia siliqua, Arbutus unedo, Erica arborea, Phoenix canariensis, Phoenix dactylifera, Laurus nobilis, Vachellia flava, Senegalia senegal, Prosopis cineraria, Aerva javanica, Prunus amygdalus, Corylus avellana, Sclerocarya birrea, Ficus salicifolia, Faidherbia albida, Borassus aethiopum, Vitellaria paradoxa, Afzelia africana, Kigelia africana, Adansonia digitata, Hyphaene compressa, and species of Boswellia and Commiphora.

[14] Thickets of semi-deciduous shrubs and low trees occur on the limestone plateau and lower slopes of Hajhir Mountains.

[14] Dense shrub thickets of Searsia thyrsiflora, Cephalocrotonopsis socotranus, and Allophylus rhoidiphyllus grow on the high mountain slopes.

Its red sap was thought to be the dragon's blood of the ancients, sought after as a dye, and today used as paint and varnish.

Other introduced mammals include the domestic cat (Felis catus), lesser Indian civet (Viverricula indica), black rat (Rattus rattus), house mouse (Mus musculus), Etruscan shrew (Suncus etruscus), and Madagascan pygmy shrew (Suncus madagascariensis).

There are many endemic invertebrates, including several spiders (such as the tarantula Monocentropus balfouri) and three species of freshwater crabs (one Socotra pseudocardisoma and two Socotrapotamon).

[15] Over the two thousand years of human settlement on the islands the environment has slowly but continuously changed, and, according to Jonathan Kingdon, "the animals and plants that remain represent a degraded fraction of what once existed.

"[15] The Periplus of the Erythraean Sea says the island had crocodiles and large lizards, and the present reptilian fauna appears to be greatly reduced.

Until a few centuries ago, there were rivers and wetlands on the island, greater stocks of the endemic trees, and abundant pasture.

The United Nations Environment Programme named unplanned urbanisation and tourism development, overgrazing, resource exploitation, invasive species, and climate change as threats to Socotra's biodiversity.

[22] The island was recognised by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as a world natural heritage site in July 2008.

The European Union has supported such a move, calling on both UNESCO and International Organisation of Protecting Environment to classify the island archipelago among the environmental heritages.