Greece Stefanos crater

A small active crater with sulfur steaming out of the soil within the big crater that represents Nissyros island S of Kos.

Take a pic with a tele lens (like this one) high up from the crater rim, then drive down to walk into the inner (Stefanos) crater where sulfuric steam is coming out of many holes. Beware of the acidic soil in the crater and the acidic sulfuric steams there as they can damage your front lens if you get too close to take pics of the sulfuric crystals forming around the vents.

Nissyros is easily accessible by boat from Kos within an hour. Then take a car or a bus to drive around the island.