We sit down to rest and try to take in all the details of this novel picture. It is undoubtedly an old volcano we are now looking down into; the spot on which we rest is only a few feet in breadth, and we can see that this narrow knife-edge is the same all round the crater. Outside of it the slope is pretty easy, but inside it descends steeply, here and there precipitously, to the edge of the cliffs which so sharply define the actual vent and, as distinctly, the lake which they enclose. Looking southwards, the crater edge gradually ascends, winding round the southern side, and still ascending as the eye follows it to the western, the opposite side, where the crater wall towers steeply up from two hundred to three hundred feet higher than it does on the east, where we are standing. The lake we judge to be about eight hundred to nine hundred feet long and two hundred to two hundred and fifty feet wide, forming a long oval, with pointed ends. The cliffs which enclose it appear to be from forty to fifty feet in height, whitish in colour, but with black streaks, where the rain, charged with carbonic acid, has poured more plentifully down their faces. These cliffs are vertical and in some places overhang the water, and from their apparently horizontal stratification are no doubt of gneiss rock. In coming up the hill I noticed a few small lumps of gneiss among the basaltic lava pebbles. The strongest feature of Trìtrìva is the sharply defined vertical opening of the vent, looking as if the rocks had been cut _clean through_ with an enormous chisel, and as if they must dip down—as is the case—to profound depths below the dusky green waters. At the northern end of the lake is a deep gorge or cleft, partly filled with bushes and other vegetation. Southward of this, on the eastern side, the cliffs are still lofty and overhang the water, but at about a third of the lake’s length they gradually decrease in height, and at the southern point they dip down to the level of the lake, so that at that part only can the water be approached. On the western side the cliffs keep a pretty uniform height all along the whole length. [Sidenote: THE CRATER]