In a great cave some miles within the edge of Mirkwood on its eastern side there lived at this time their greatest king. Before his huge doors of stone a river ran out of the heights of the forest and flowed on and out into the marshes at the feet of the high wooded lands. This great cave, from which countless smaller ones opened out on every side, wound far underground and had many passages and wide halls; but it was lighter and more wholesome than any goblin-dwelling, and neither so deep nor so dangerous. In fact the subjects of the king mostly lived and hunted in the open woods, and had houses or huts on the ground and in the branches. The beeches were their favourite trees. The king's cave was his palace, and the strong place of his treasure, and the fortress of his people against their enemies.

Bilbo had all he could do to keep up with the torches, for the elves were making the dwarves go as fast as ever they could, sick and weary as they were. The king had ordered them to make haste. Suddenly the torches stopped, and the hobbit had just time to catch them up before they began to cross the bridge. This was the bridge that led across the river to the king's doors. The water flowed dark and swift and strong beneath; and at the far end were gates before the mouth of a huge cave that ran into the side of a steep slope covered with trees. There the great beeches came right down to the bank, till their feet were in the stream. Across this bridge the elves thrust their prisoners, but Bilbo hesitated in the rear. He did not at all like the look of the cavern-mouth and he only made up his mind not to desert his friends just in time to scuttle over at the heels of the fast elves, before the great gates of the king closed behind them with a clang.