Socotra Island is about 350km south of Yemen, where it politically belongs to. It is located in the Indian Ocean, off the Horn of Africa. Socotra is part of an archipelago, but all the other islands are small. The largest of these are Abdu l-Kuri and the Al-Ikhwan Islands. Socotra is a piece of continental crust, which was detached from the main continent and moved by tectonic forces. Isolated islands or archipelagos in the middle of the sea are rather common, and there are numerous similar islands, but those islands are of volcanic origin, formed in the middle of oceanic plates by hot spots.
Being isolated from the next continent for about six million years, since the Pliocene, Socotra has a highly endemic fauna and flora. The most famous plant, and the islands dragon's blood tree. The island has three different geographical terrains, narrow coastal plains, the Haghier Mountains which rise up to 1525 meters, and a karstified limestone plateau. The island has many caves, one of them is very easy to visit with guides, a sort of show cave.
The speleological exploation of the island was mostly done during six Belgian expeditions, between 2000 and 2004. The result of those expedition is a report which is published by the Speläoclub Berlin (SCB), see link below. 28 caves were explored and 22.7km of cave surveyed.