While staying on the Greek island of Kos during the summer of 1996 my wife and I made a one day trip to Nysiros. This small volcanic island is part of the Dodecanese Islands. Nysiros is almost completely round with a diameter of 6km. Most interesting feature is the sulfurous 4 km wide caldera. The caldera was formed after the magma chamber of the volcano imploded. Violent earthquakes and steam blasts accompanied the most recent hydrothermal eruptions in 1887.  Inside the caldera a 250m wide circular depression can be found. This crater can be entered but you need good shoes, a bad nose and a lot of drinking water. The ground is 50°C hot, there is no wind at all and it smells very sulfurous. Photo's are taken with a small pocket camera.