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broad "highway" which sometimes widened into a hall and which followed the circumference of the crater wall. This "highway" alone was over a half-mile in length. For the most part, the floor of the passages was damp, muddy, and strewn with broken rock.

   The system of tunnels was filled with strange and threatening noises. Hot steam piped, gurgled, and hissed from hundreds of places in the ground, carving its way through mud and potholes and melting the ice on the walls and ceilings, which dripped continuously onto the ground. At other points there were streams of foul-smelling, poisonous gases. In many places the path was not only dark but shrouded with clouds of vapor which concealed everything from view. All the moisture the crater contained rained down into the depths. Apparently a pond or a lake is located somewhere deep inside this underworld.

   A warm draft was blowing even at the tunnel entrances, more than 13,000 feet high in the crater wall. The temperature was 40 C. But on top of everything else, it was hot inside the tunnel system! The steam in the corridors was as hot as 560 C, and at one point the temperature of the rocky floor was 860 C.    

   Struggling against the heat, vapor, water, and gas, the geologists recorded, measured, and made charts of what they found. They marveled at the steep descents and at the cathedral-like grottoes which had been melted out of the ice. At one point, when the ice above them was four hundred feet thick, they made two amazing discoveries. On the ground before them lay the remains of a bird which as a rule inhabits the coast sixty miles away, and above them in the icy ceiling of the corridor they found a red woolen glove!       

   Mysterious discoveries ought to occur in an adventure, and this adventure had its share. Up