Nisyros is together with the volcanoes of the Cos caldera the east edge of the Aegean Arch with its active volcanoes Methana, Milos, Santorini. The Nisyros volcano is the most active remain of the Cos caldera that exploded aprox. 150.000 years ago. Nisyros, Yali, Strongyli, Pyrgoussa, Pahia and Kefalos (at Cos) are the remains of a zone that is considered to be still active. A Magma chamber below Nisyros is only 3-4 km deep and still rising up. Since 2000 when the Nisyros research program of the GEOWARN-Team started, the temperatures of the fumaroles have been changing from 98 C to 103 C in 2004. There was also a high tectonic (earthquakes) activity in the last years and so a program to prevent volcanic hazards is still ongoing. Nisyros is a very interesting place (not only) for geologists, because here you can study all kinds of volcanic rocks and you can even walk into the biggest hydrothermic crater on earth. Also the nature is a great thing to discover. Walking in the beautyful mountains is something unforgetable!