Argentinian artistLeandro Erlich created this installation, simply calledThe Swimming Pool, forThe 21st Century Museum of Contemporary Art in Kanazawa, Japan. A 10cm layer of water over a piece of glass separates above from below. It must be a pretty serious piece of glass; some back-of-the-envelope math based on the published dimensions gives 1,100 kg (2400 lbs) of water that it has to support. Plus its own weight.