How could Gollum follow the Fellowship out of Khazad-dum?

Question

Gollum starts following the Fellowship soon after they enter Moria. Frodo hears his faint footsteps throughout their journey to Balin's tomb in the Hall of Records. But how could Gollum follow them out of Moria?

From FotR, I gather that the situation looks like this:

• In the Hall of Records, the orcs attack, and the fellowship flees through a small passage. Gandalf blocks the way by collapsing the door. So Gollum could not follow them on this way (without the Ring, it seems very unlikely that he somehow slipped past all the orcs and Gandalf and was not noticed by any of the Fellowship).

• The "main" way through the great hall was blocked by a large crack filled with fire. The company realizes that it was made by the orcs to block the way to the great gate/east entrance and that they were lucky to have been forced to take the other way. Only after trolls put down large blocks of rock the orcs are able to pass the crack. Again, with all the orcs it seems unlikely that Gollum slipped through.

• The last bridge was made very narrow by the Dwarves so that an invading enemy had to pass it in single file, making it easy to defend for the Dwarves on the other side. This implies that it was the only passage out of Moria to the east gate. Since it was destroyed by Gandalf, Gollum could not pass it.

So how did Gollum manage to get out of Moria, quickly enough for him to not loose track of the Fellowship? How did he find a way out while avoiding all those orcs and trolls? How could such a way even exist?

Answer 1

This was discussed on the Barrow Downs forum.

One theory which I find plausable is that Gollum got out of Moria before the Fellowship.

Gollum had actually originally entered Moria from the east, and had been there a while before he started trailing the Fellowship, he certainly had no trouble surviving:

What then happened to Gollum cannot of course be known for certain. He was peculiarly fitted to survive in such straits, though at cost of great misery.

(Unfinished Tales, The Hunt for the Ring)

And he did eventually get to find his way around (although it took him a while):

but he became lost, and it was a very long time before he found his way about.

(Unfinished Tales, The Hunt for the Ring)

So it's definitely possible that even if he didn't get out before the Fellowship, he at least would have known of alternate routes to the East Gate (after all, the orcs also leave Moria to continue their pursuit, so there must be other such routes).

Answer 2

Gollum was sent from Mordor on a mission by Sauron

You say that Gollum could not follow the Fellowship out of Moria, because:

The "main" way through the great hall was blocked by a large crack filled with fire. The company realizes that it was made by the orcs to block the way to the great gate/east entrance and that they were lucky to have been forced to take the other way. Only after trolls put down large blocks of rock the orcs are able to pass the crack. Again, with all the orcs it seems unlikely that Gollum slipped through.

However, you overlook the fact that Gollum was a servant of Sauron, the same as the Orcs. He was sent from Mordor on an errand for Sauron, a fact reported by Aragorn at the Council of Elrond.

‘He is in prison, but no worse,’ said Aragorn. ‘He had suffered much. There is no doubt that he was tormented, and the fear of Sauron lies black on his heart. Still I for one am glad that he is safely kept by the watchful Elves of Mirkwood. His malice is great and gives him a strength hardly to be believed in one so lean and withered. He could work much mischief still, if he were free. And I do not doubt that he was allowed to leave Mordor on some evil errand.’

The Orcs had assisted him to escape from the Wood Elves in Mirkwood, as reported by Legolas at the Council.

‘It was that very night of summer, yet moonless and starless, that Orcs came on us at unawares. We drove them off after some time; they were many and fierce, but they came from over the mountains, and were unused to the woods. When the battle was over, we found that Gollum was gone, and his guards were slain or taken. It then seemed plain to us that the attack had been made for his rescue, and that he knew of it beforehand. How that was contrived we cannot guess; but Gollum is cunning, and the spies of the Enemy are many. The dark things that were driven out in the year of the Dragon’s fall have returned in greater numbers, and Mirkwood is again an evil place, save where our realm is maintained. ‘We have failed to recapture Gollum. We came on his trail among those of many Orcs, and it plunged deep into the Forest, going south. But ere long it escaped our skill, and we dared not continue the hunt; for we were drawing nigh to Dol Guldur, and that is still a very evil place; we do not go that way.’

So Gollum could count on the Orcs for assistance in Moria, he had no need to evade them in leaving. A large force of Orcs arrive in the Golden Wood with him, so obviously the Bridge was quickly repaired or replaced, to permit that force to pursue the surviving members of the Fellowship at once.