At the southern tip of Corsica, limestone cliffs overlook the sea at 60 m (197 ft) high. The entrance to the port of the citadel city is a natural maritime corridor of 1,500 m (4,921 ft) long. Created in 1999, the Strait of Bonifacio Nature Reserve covers 80 000 hectares: is the largest nature reserve in metropolitan France. Under the waters, an animal at borders between vegetal and mineral thrills the divers: the red coral grows between 5 and 700 m (16 and 2,297 ft) depth.