Djibouti is a small strategically located country on the northeast coast of the Horn of Africa. It is situated on the Bab el Mandeb Strait, which lies to the east and separates the Red Sea from the Gulf of Aden. The capital is the site of a modern deep-water port that serves Indian Ocean and Red Sea traffic and hosts a French naval base. Djibouti city is also the railhead for the only line serving Addis Ababa, capital of neighbouring Ethiopia. The country is internationally renowned as a geologic treasure trove. Located at a triple juncture of the Red Sea, Gulf of Aden, and East African rift systems, the country hosts significant seismic and geothermal activity. Slight tremors are frequent, and much of the terrain is littered with basalt from past volcanic activity.