The Underwater Waterfall, located off the Le Morne Peninsula in southwest Mauritius, is a natural optical illusion formed within the island’s coastal lagoon. Visitors can view the phenomenon from viewpoints such as Le Morne Brabant or experience it more clearly through helicopter or seaplane tours, which provide an aerial perspective of the effect. The site is notable because it is not a real waterfall, but an illusion created by ocean currents moving sand and silt over a steep underwater drop, producing the appearance of cascading water beneath the surface.