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Remote and isolated, the Socotra archipelago is often described as the "most alien-looking place on Earth." The islands, part of Yemen, are scattered in the Arabian Sea, with Socotra, the largest island, designated a UNESCO World Heritage Site. But while once a discerning destination for hardcore adventure tourists, visitor numbers have dwindled since the outbreak of the Yemeni civil war in 2015.

Browse this gallery and get an idea of what this unworldly island looks like.

(Photo: Flickr/CC BY-SA 2.0)

▲Socotra is the largest island in the Socotra archipelago. It's located off the coast of Somalia, between the Guardafui Channel and the Arabian Sea.

▲Despite its proximity to the east African coast, this mysterious territory is officially part of Yemen.

▲Before the Yemeni civil war, Socotra was an exceptional destination for adventure tourists. Indeed, the island received over 1,000 tourists each year until 2014.

▲Remote and isolated, the archipelago is of universal importance because of its biodiversity, including rich and distinct flora and fauna. The iconic dragon blood tree (pictured) is native to the archipelago. (Photo: Flickr/CC BY-SA 2.0)

▲According to UNESCO, 37% of Socotra's 825 plant species are not found anywhere else on Earth.

▲Similarly, 90% of its reptile species and 95% of its land snail species do not occur anywhere else in the world. (Photo: Flickr/CC BY 2.0)

▲Nature sanctuaries, national parks, and areas of special botanical interest encompass about 75% of the total land area.

▲This area of the island has the highest concentration of dragon blood trees, as well as many other tree species.

▲Pictured is a freshwater mountain lake sunk near the Homhil plateau.

▲Besides the dragon blood tree, Socotra is also recognized for other weird and wonderful flora, such as the golden bottle tree.

▲Indeed, travel inland and the island starts to take on a distinctly unworldly appearance. Pictured on a hillside in Wadi Diksam are Socotran desert roses, whose fat trunks are adapted to store water.

▲Seen here is the inhospitable Diksam plateau. (Photo: Wikimedia/CC BY 2.0)

▲The odd-looking cucumber tree is another species endemic to the archipelago. (Photo: Wikimedia/CC BY 2.0)

▲Hanging on by its roots is this frankincense tree. Its aromatic resin is used in incense and perfumes. (Photo: Flickr/CC BY 2.0)

▲Pictured are the impressive granite spires of the Hajhir massif, the highest point on the island.

▲The mountain range summits out at 1,500 m (4,900 ft) above sea level. (Photo: Wikimedia/CC BY-SA 4.0)

▲The distant Hajhir Mountains provide dramatic contrast against a tranquil oasis set near the island's capital, Hadibu.

▲The archipelago also supports significant populations of land and sea birds, including the threatened Socotra cormorant.

▲The Socotra starling is endemic to Yemen, including the archipelago. (Photo: Wikimedia/CC BY-SA 2.0)

▲Around 1,000 Egyptian vultures call Socotra home, the highest concentration of this endangered bird found anywhere in the world.

▲Ground-dwelling creepy-crawlies include the Socotra island blue baboon. This endemic spider species is a member of the tarantula family. (Photo: Flickr/CC BY-SA 2.0)

▲Marine life on Socotra is also very diverse. Pristine coastal waters support 253 species of reef-building corals.

▲There are also 730 species of coastal fish, and 300 different species of crustacean. (Photo: Flickr/CC BY-NC 2.0)

▲Storm clouds approach Detwah lagoon. This is where Socotra's finest beach can be found. (Photo: Flickr/CC BY 2.0)

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Seen here is the approach to Detwah lagoon and the spectacular beach near the port of Qalansiyah, the second biggest town on the island.

▲Pictured are the ancient ruins of Dihambri, near Qalansiyah. The island served as an important trading post back in the 3rd century CE.

▲Some of Socotra's natural wonders are hidden from the outside world. Halah cave, located on the east side of the island, is several hundred meters deep and for the most part remains in total darkness.

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Another celebrated location is the Archer sand dunes. Archer is located on the north-east shore of Socotra.