Nisyros (Greek: Νίσυρος; also transliterated Nissiros; see also List of traditional Greek place names) is a volcanic Greek island located in the Aegean Sea. It is part of the Dodecanese group of islands, and lies between Kos and Tilos. Its shape is approximately round, with a diameter about 8 km, and its area is 41.6 km². Several other islets are found in the vicinity of Nisyros, the largest of which is Gyali. The island has a mountainous interior and in its center several craters are found. Its coasts are generally rocky or pebbled, but there are also a few sandy beaches. The volcano is currently active (not erupting), and fumaroles are found at the craters. The latest eruption was in 1871 and earthquakes are not infrequent. According to Greek mythology, the island was formed when Poseidon cut a part of Kos and threw it on the giant Polyvotis to stop him from escaping. The ancient name of the Nisyros was Porphyris. The main town and port of the island is Mandraki. Other villages are Paloi, Nikeia and Emporios. According to a 2001 census, the resident population is 938, although in summer it is augmented by many tourists as well as expatriate Nisyrians who visit the island for their vacations. Tourism is not so heavily developed as in other Greek islands. On Gyali there are deposits of perlite and pumice which provide much of the wealth of the island. The island used to be self-sufficient, and many crops were grown on its terraced slopes. Today, though, they are cultivated on a smaller scale. There is a health spa with sulphurous waters that used to be world-famous in the first decades of the 20th century. A traditional product of Nisyros is soumada, a non-alcoholic almond-flavoured drink. The patron saint of the island is Saint Nikitas. Many Orthodox Christian churches are found on the island, as well as four monasteries which are not inhabited by monks today, although various celebrations take place in them. The largest monastery is the one of Panagia Spiliani (Blessed Virgin Mary of the cave) at Mandraki. It is built beside the medieval castle erected by the Knights Hospitaller who conquered the island on 1315. Ancient walls, dating from the 5th century BC, part of the acropolis of the island, are found near Mandraki. There is a heliport. Nissiros is a small volcanic island situated between KOS and TILOS islands .The capital and port of Nisyros is Mandraki,set inthe northwest at the foot of a step Hill. The whiteness of the Houses forms a striking contrast to the dark volcanic earth. he castle erected  by the Knights of John loons above the small town ,while a chapel nearby dedicated to Panayia tis Spilianis ,the patroness of the island ,clings to the tip of the rock. Built in 1600 it is linked with many traditions and has a lovely 18th century iconostasis. The islands hot springs ,fabled since antiquity and still in use today, you can found it as Loutra ,just 1,5 km from Madraki .East of Loutra is the picturesque Fishing Village of Pali. Another Village ,EMBORIOS ,lies to the  southeast of Mandraki ,in the interior of the island ,in a lush area with mineral springs  and planted in olive trees , fruit trees ,fig trees and grapevines. You have to go  almost to the middle of  Nisyros to the Lakki Plateau to see the crater of the  extinct volcano  ,Polybates. It is  260 meters in diameter  and 30 m meters deep with steps leading down  to its center  .The reek of sulphur fills the surrounding air ,with the scenery could  belong to the  moon. In the south of the island the chumming village  of Nikia perches on the crest of the Hill 400 meters above sea level. It's white  houses with their brightly colored doors and windows and tile roofs are an attractive, complement to the greenery that abounds in the district.  Nsyros  is blessed with many lovely Beaches: Mandraki beash,Hochlaki beach ,Agia Irini Beach,  Avlaki Beach and Giali beach located opposite of the island of Nisyros.