ater is Earth's oddest liquid, a willy-nilly bender of all the rules of science. Good thing, too, because if it our oceans and rivers and lakes - the stuff we drink to stay alive - would exist as vapour, and the planet would be bone dry. Water's rebellion also causes it to expand when it freezes, so that ice counterintuitively floats on water. If lakes and rivers froze from the bottom up instead of forming a thick layer on top, much underwater life would be extinguished. Another useful advantage is that ice is structurally hard but is sufficiently malleable for it to be fashioned into sculptural works, such as those at the annual Harbin International Ice and Snow Sculpture Festival on the frozen Songhua River in north-eastern China. It's the world's largest such festival, and comprises entire theme parks built of ice, plus carnival activities and sports ranging from ice football to ice sailing, sledding, skating and skiing competitions, plus ice art exhibitions, snow film screenings and - of course - weddings on ice. It runs from around Christmas time until the end of February.
