As well as the main island Koufonisi, the region includes smaller islets – Stronguli, Makrouli and Marmara to the north, with only Trachilos to the south.
The sea comprises 60% of the designated territory. Koufionisi itself is a small island with a hot and dry climate. It has both sandy and pebbly shorelines. The marine component comprises a good representative example of what exists, and is well maintained: caves, reefs and seagrass meadows. No permanent human presence on the island is permitted: visitors come in the summer holiday months, but tourist activities are low-key.
The importance of the island comes from its geographical position and the excellent condition of its unusual eco-habitat. Basically, it has a deep-rooted North African element, which otherwise is not much evident in Crete (though see Vai). There are endemics, at the north limit of their distribution .. like Zygophyllum album, Helianthemum stipulatum (a rock rose) and Astragalus peregrinus spp peregrinus (a milk vetch): these on Koufonisi are the only known specimens in all of Crete or Greece.
The marine aspects are also very important.
Finally the island adds historical and archaeological value to the biological: an ancient theatre is known. The archaeological potential here is great, but as yet far from explored fully.