Copenhagen, Denmark-born artist Jeppe Hein is one of those artists that doesn't just want you to look at his artwork, he wants you to interact with them. Known for his sculptures and installations where art, architecture, and technical inventions intersect, he's the one behind some of the most interesting benches, mirrors and fountains you'll ever come across.
In Triangular Water Pavilion, he created an equilateral triangle with two walls made of spy mirror glass and one wall made of water that rises up over a basin. When you move close to the water wall, a sensor is activated and the visitor is invited to step inside, as the water wall falls down. Once inside, the water starts flowing again, "trapping" the viewer in the space of water and mirrors.
Since the glass walls are transparent on one side and reflective on the other, from the inside, it looks like you're surrounded by walls of water. The mirrors create a "multiple optical effect" which makes everything seem to dissolve around you.