Greece is characterized by an extremely fragmented, rugged landscape hosting a great diversity of ecosystems and an outstanding biodiversity. Almost 5% of its extensive coastline consists of ecologically sensitivewetlands. Two thirds of the total population live no further than 2 km from the coast and most of the important urban centers are coastal, while almost all of the tourist infrastructure is divided among islands and the coastal mainland.
Each national park consists of a core and the area surrounding it. 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. The surrounding area must be larger than, or at least equal to, the size of the core.