That vent in the cliff pours out its hot gases with such a force that it sounds like the whistle of a locomotive and the sound is plainly audible in the bedchamber three miles distant. Day after day and century after century this safety valve has been sounding and it is sounding as we write,—an awful sound to unaccustomed ears, a pleasant one to those who live within the radius of this wide belt of volcanic activity, for it signifies safety from violent eruption as long as the generating forces beneath the surface are continually spent. It has been estimated that there are no less than 250,000 tons of sulfur in this place and it is constantly increasing by sublimation from below. The hot area is on a line with hundreds of others of a like character, active or temporally quiet, extending in a line from _Krisuvik_ to _Thingvallavatn_, a distance of thirty miles. This line is also on the main diagonal of volcanic activity extending from _Reykjaness_ to _Mývatn_ in the northeast. Over five hundred square miles of the fire peninsular is of recent volcanic origin and the subarea is highly heated. Numerous hot springs abound, fumaroles are without number, earthquakes are many, lava frequently issues from the fissures in the mountain sides and there is evidently beneath the crust of earth another Phlegethon, that flaming river of the under world in whose channel flowed flames instead of water. Around _Krisuvik_ there are many extinct craters filled with water. _Gestavatn_, Guest-Lake, near the solfatara is of this character. It is said to be without a bottom but this is because it is funnel-shaped and very deep in the center, which marks the old volcanic tube. It is strange that in the midst of this heated territory the waters of this lake should be icy cold. It is a beautiful sheet of water, so deep and so clear that it holds the reflected blue of the sky appearing now to be a sheet of lapis lazuli and now a sapphire blaze. Around its margin a rim of grass and flowers thrive but beyond the ring volcanic rubble and patches of sulfur and clay displace the vegetation. At a greater distance the brilliant surface of _Kleifavatn_, Cliff-Lake, reflects the encircling bluffs and ragged gorges within whose recesses a small herd of reindeer seek seclusion from the traveller. Down by the sea the _Eldborg_ stands, well worthy of inspection. It is a mound-shaped crater with very thin walls. It would seem as if Pluto was sparing of his solid material when he built this funnel, for he made it as frail as possible as if in haste to pour out the molten matter in a flood upon the surrounding plains. The shore side of the mountain is the home of countless puffin, skua and other aquatic birds. Along the sands of the sea the seal bask in the sunshine or crawl back to their element with the retreating tide. Taken as a whole, the _Krisuvik_ region is a place of fascination, even though one stands on the thin crust of sulfur that feebly supports him,