The closest to a real waterfall is the illusion of one off the coast of Le Morne on the southwest of island of Mauritius. The sand and the slit on the ocean floor that deposit floor through the area make it look like they are pouring a waterfall.
The underwater waterfall looks so real and for a long time people thought it was real. The sand that contributes to the waterfall illusion is pulled by the currents of the ocean from a higher coastal shelf and into the deeper water further out of the sea.