Nisyros covers an approximate area of 41 sq.kilometers and the total length of the coasts is 24 kilometers. It is situated northwest of Rhodes, between Kos, Tilos and Astypalaia. This island is on the easternmost edge of the active volcanic arc of the South Aegean, which icludes a geographical zone beginning from the Isthmus of Corinth, it crosses the peninsula of Methana, Milos, Thira and ends in Nisyros. This zone hosts all the active volcanoes of Greece and was formed by the outlet of the magma to the earth surface. The successive layers of lava and ash did not denude the island from its vegetation; on the contrary, through the terraces (vastadia) they helped in the development of the crops (oak, olive and almond trees) and the organized export of almonds, oak trees and figs. At the same time, they formed the green image of the island in contrast to the barren landscape that one encounters in the other volcanic islands of the Aegean.
At least 30 species of wild birds and a number of endemic birds have been recorded.
Around Nisyros, there are the islets of Gyali, Kantilioussa, Pyrgoussa, Stroggili and Pachia. The glassy and hard volcanic rock of obsidian from Gyali has been a raw material for the manufacture of cutting tools since the Neolithic Period. The pumice became an object of systematic exploitation turning the island into a major export center. One of the hardest rocks, the basaltic andesite, has proven to be a suitable building material, as highly competent stonecutters used this volcanic material to build both sides and the intermediate filling for one of the most well preserved fortifications in the Aegean, the wall of the ancient city in Mandraki.