Greece is characterized by an extremely fragmented, rugged landscape hosting a great diversity of ecosystems and an outstanding biodiversity.
A temperate climate is found in Central and Eastern Macedonia as well as in Thrace at places like Komotini, Xanthi and northern Evros; with cold, damp winters and hot, dry summers.
The tradition of protected areas in Greece dates back to Ancient Greek times and the Altis and sacred grove at Olympia, amongst other sanctuaries.
According to Greek Law the core cannot be smaller than 15,000,000 square metres (5.8 sq mi), with the exception of marine national parks.
[citation needed] In the core of the national park, only scientific research, mild recreational activities, and the acquiring of environment related information are permitted.