Gobustan's volcanoes erupt cold. The grey mud welling out of these cones is no warmer than the air around it: nothing here is molten, and what drives the eruption is gas. Beneath the South Caspian basin lies sediment up to 25 kilometres thick, compressed until the methane and water trapped inside are under enormous pressure. That pressure forces a slurry of clay, brine and stone up from kilometres below, building a cone a metre or three high rather than a mountain. Azerbaijan has more of these than any country on Earth, roughly half of the world's 700 or so, and the field at Dashgil, south of Gobustan town, is the one most people come to see. In 2009 the country's mud volcanoes were voted one of the 28 finalists for the New7Wonders of Nature.
Out on the plateau, the ground does the talking. Twenty-odd cones stand on a cracked grey plain, each holding a crater of thick mud that swells into a dome, hesitates, then bursts with a wet plop; between them lie broad, soupy pools where gas breaks the surface in slow rings. The air carries a faint smell of petrol and sulphur — the reservoirs feeding these vents are the ones that made Azerbaijan an oil country. Dried mud flows harden into a tight polygonal crust that cracks underfoot, and past the last cone the Caspian lies flat on the horizon. In March and April the surrounding steppe briefly greens and flowers, the only colour the place gets; by summer it is brown again. Since June 2024 the field has had a tourism complex: marked footpaths, a quad-bike track, a zip line and an observation tower, open daily from 10:00 to 19:00. Visitors must stay five metres back from every vent — the mud may be cold, but the lip of a crater is slick and undercut.