At the Mountains of Madness by H.P. Lovecraft

I have said that our study of the decadent sculptures brought about a change in our immediate objective. This, of course, had to do with the chiseled avenues to the black inner world, of whose existence we had not known before, but which we were now eager to find and traverse.

From the evident scale of the carvings we deduced that a steeply descending walk of about a mile through either of the neighboring tunnels would bring us to the brink of the dizzy, sunless cliffs about the great abyss, down whose side paths, improved by the Old Ones, led to the rocky shore of the hidden and nighted ocean. To behold this fabulous gulf in stark reality was a lure which seemed impossible of resistance once we knew of the thing -- yet we realized we must begin the quest at once if we expected to include it in our present trip.