[IC] Chapter 2-5: You're whirling 'round...

[DM Surranó]

indeed, it's not all dry up to the waterfall. The pool at the bottom of the waterfall gets steep deep at the point when the rushing water breaks its surface but part of the water protrude into the cave where the party is, in the approximate form of a semicircle about 15 feet in diameter. The other side of the waterfall, of course, is a much larger "pool". Most of the surface bobs and waves intensively as one would imagine at the bottom of a waterfall but the edge is calm enough to provide a decent picture if used as a surface for scrying.

OOC - I guess this is why you asked I don't know if it's explicitly mentioned anywhere that the actual audiovisual feedback of the magical sensor is reflected by the mirror/font/pool (focus depending on class) or it's "just" a mere focus and the image is visible in your mind but it feels just right. My perception of how the Divination (scrying) subschool is described it should be the other way around (it's your extra sensory organ). Apart from that, it's not explicitly mentioned whether the image is visible (and voice is audible) for everyone like a figment or just for the caster like a phantasm. The spell says "you" which suggests a mental image. But I'm happy either way and not really concerned by the added value that multiple spectators' sensory capabilities may increase effectiveness (e.g. if the caster didn't have darkvision but someone else of the party did then the party as a whole could perceive more than the caster alone)

As a classical non-D&D example, Galadriel's mirror reflected the image Frodo saw (it wasn't a "mental image" in this sense) but she could not see the image. She just knew.