A scouting adventure does not reveal very much, except that the tunnels become more rough-hewn and dark. Soon after the throne room, there is another descent, this of about a hundred and fifty feet, mostly through spirally stairwells and switchback ledges, much like you saw earlier. There are few places where a fall would be more than twenty feet, however; the way has been cut down through the rock, and does not stop until you reach the water table of the giant cave, where the waterfall had to be fixed with planks.
The difficulty can't ever be too much. From the images, prisoners in bondage had to make these passages and be kept alive until they could be hurled from the cliff.
A few hours gets you to the water table, and a bit beyond. There's a slow, gurgling stream, a foot or so deep, cold as blazes, about twenty feet wide. And from what you can see, the passage switches back and forth across this stream, often with a ceiling no higher than 7 or 8 feet, so that there's no way to avoid getting your feet wet.
It must have been miserable for the prisoners, but presumably the froglings would not have minded the water.