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