Ключевые слова: boiling, bubble, colorful, colors, crack, danger, earth, earth crust, energy, environment, fissure, geology, geothermal, geothermal activity, geothermal area, grey, guy, heat, hissing, hole, hot, hverir, hydrogen sulfide, iceland, krafla, mineral, mud, mud pool, mud pot, mud pots, myvatn, namafjall, namaskard, natural, rock, rotten eggs, scalding hot, simmering, smell, smoke, smouldering, soil, steam, steaming vent, sulfide, sulfur, sulphating, surreal, volcanic,