Most moving-water Lego scenes I have come across lean on static swoosh pieces or a visible conveyor of parts chugging along in plain sight. kbrtosser went a different way with this island build: a multi-tiered cliff in dark and light grey with an actual continuous cascade running down the rock face into a baseplate pool, all depicted as a natural waterfall and lake scene.
The mechanism is the part worth studying. Two sub-assemblies make it work. The first pairs a 1x4 light grey plate with two translucent blue 1x2 tiles laid horizontally. The second spreads four of those tiles vertically across the studs, each one seated dead center in the underside groove. These alternating assemblies snap onto every other link of a Technic tank tread, which stands upright inside the model and turns on a drive axle. Since the tiles overlap as the track travels, the falling water reads as one unbroken sheet with no gaps, and Technic liftarms, gears and axles provide the drive. The finished mechanism runs hidden within the rock cliff itself.
One detail stands out: the insistence on tiles rather than plates. The maker explains that the ridges on the underside of plates stop anything from sitting centered, so tiles are the only workable option there. That seems like a smart constraint to flag openly, since anyone copying the technique would hit the same wall with plates.
The one open question for me is the base of the fall. A suggestion floating around is that the clear pieces at the foot of the waterfall could climb higher before the pool takes over. Whether that would improve the transition from falling water to lake seems worth testing.
Project by kbrtosser. Watch it on their YouTube channel: