How do all the inhabitants of this module get in and out? There is one secret entrance, but that does not seem like it is the entrance and exit for everyone.
Here's the answer that I finally worked up:
That's a better puzzle than I first thought. There are quite a number of open stairways connecting the levels, but some of the rooms are guarded by monsters that don't make sense to be passable. I think we can conclude that only a small number of leader-types make that trip.
Path #1: For figures who can fly/levitate, you could most easily go through: 3-210-301-306-307. Creatures at 306 and 307 are noted as recognizing leaders/signs of power.
Path #2: Walking only, could go: 109-201-217-222a-312. Disadvantage here is guards in 217/218 are noted to only let through agents of Water Temple, and stairs at 222a are "dusty". Creature in 312 behavior is unclear, but is certainly more than intelligent enough to respect temple leaders.
Path #3: Or: 109-153-246-227-209a-314-311-308-307. This is a bit longer, but has the advantages that every area on the path is clearly traversible, has respectful guards, or non-encounters if you pass through without stopping. Stairs at 153 are "safe and sound". This path even has two drinkable fountains along the way at which you can refresh yourself!
Paths #1 and #3 require knowledge of certain secret doors, but Path #2 does not. If I were leading a sally party out of the lowest level, I'd probably kick the residents out of areas 217 and 312 and take my monsters through that way.
Hat tip to Danny Barry for the original question.