Necker Belle yacht has a top speed in excess of 20 knots, being rare in the world as being able to do so. The Necker Nymph excursion submersible also operates from the yacht. It is reputedly the first-of-its-kind "aero submarine", buoyant when not under power. Necker Belle The Necker Belle is a 105-foot (32 m) private charter catamaran yacht, offered through Virgin Limited Edition and based at the resort Necker Island. The "Belle" superyacht is one of the few luxury sailing catamarans in the world. Prior to being purchased by Richard Branson's Virgin, the yacht was called "Lady Barbaretta", and cost £5.3
Necker cube in the Psychology Department of City University, London, were provided with assignments to measure their Introversion-Extroversion orientations by the time it took for them to switch between the Front and Back perceptions of the Necker Cube. The orientation of the Necker cube can also be altered by shifting the observer's point of view. When seen from apparent above, one face tends to be seen closer; and in contrast, when seen from a subjective viewpoint that is below, a different face comes to the fore. The Necker cube is discussed to such extent in Robert J. Sawyer's 1998 science fiction novel