Beyond the Crystal Cave - your experiences?

[Stormrunner]

Also, perhaps you can tell me since you have the module with you and I don't - do the PCs know about this time differential? Because if they don't - they could spend a lot more time in there and not know what is happening. . .

They are not told directly, but there are some clues. The PCs know before going in that in the Garden it is "always summer"; that Porphorio was a powerful wizard; that he and his love "should lie together for all eternity"; and that other adventurers who entered the place "returned after a long absence, their minds and memories curiously disturbed". In the entrance cave they encounter a "frozen" waterfall; close examination shows that it is not frozen but verrrry slow, and the water gradually speeds up the farther it gets from the source.

So while they do not know the details, alert players should be expecting some sort of "time stop tricks" by the time they enter the Garden proper.