The largest island, also called Socotra, is about 95% of the landmass of the archipelago. It lies some 240 kilometres (150 mi) east of the Horn of Africa and 380 kilometres (240 mi) south of the Arabian Peninsula. The island is very isolated and through the process of speciation, a third of its plant life is found nowhere else on the planet. It has been described as the most alien-looking place on Earth. The island measures 132 kilometres (82 mi) in length and 49.7 kilometres (30.9 mi) in width.
Socotra is part of the Republic of Yemen. It had long been a part of the 'Adan Governorate. In 2004, it became attached to the Hadhramaut Governorate, which is much closer to the island than 'Adan (although the nearest governorate is Al Mahrah).