Canals, Amsterdam, Netherlands. Although it can seem like a confusing tangle, it's good to remeber that the basic layout of Amsterdam is like a spiderweb of semi-circular canals, with straight spokes of streets (and the occasional canal) intersecting.

Bridges like this one tie the whole thing together (as well as adding visual charm).

All canals are fresh water and three meters deep, except for the main canal which is six meters deep.