when you go down one of those round sewer entrances, it'll be behind some encounters with an obnoxious-short-troll, and behind the subsequent boss-fight with guy the short-troll(with fire traps) is saying is his master.
The round sewer entrance is probably the closest one to the teleport in the crows nest area (within an arrow's shot or two if there were no obstacles).
If you need more exact dirs, I'd have to go back to the area...
hope that helps.
