LotR -- Book 2 - Chapter 09 - The Great River

[The Saucepan Man]

Originally Posted by the phantom

That made me wonder, how did Gollum get out of Moria? Didn't the dwarves design Moria so that the bridge that Gandalf broke was the only way to get in or out from the east? If so, are we supposed to assume that the Orcs had made new exits or what?

Gollum's Exit From Moria

How did Gollum escape Moria?

Gollum exiting Moria

Nothing definitive, but a good deal of informed speculation.