Argentinian artist Leandro Erlich created this illusion of people walking underwater called The Swimming Pool, for The Century Museum of Contemporary Art in Kanazawa, Japan. It's a piece of glass with water on top of it, and empty space on the bottom.
Goblet Illusion -Rubin's vase is a classic example of multistable perception. The brain makes figure-ground distinction between the vase in the center (which is usually recognized first) and the contour of 2 faces by sides. (by Edgar Rubin)
Suju, Explorers of the Human Body: In the Blink of an Eye, Part 1