Many of Amsterdam's canals were filled in around the start of the 20th century, mainly for sanitary reasons. The remaining waterways are still pretty filthy, but there's nothing like seeing Amsterdam by boat - just keep your eyes up and don't trail your eating hand wistfully in the water. Amsterdam becomes even more picturesque from a duck's perspective: the houses look impossibly higgledy-piggedly, leaning, looming and jostling on both sides of the canal; bridges arch over the water, some of them opening for tall water traffic.
There are numerous tourist boats doing the rounds, and it's also possible to rent a pedal boat, if you're feeling energetic. Of course, if the canals freeze over in winter, the boats get stuck and there's skating to be had. Amsterdam frozen over is a wonderful place: the locals dust off their ice skates, children and dogs scramble around, and vendors sell hot chocolate, glühwein and soup. Watch out for thin spots in the ice, especially under bridges and at the edges: people die under the ice every year.

