Canals & Boat Tours, Amsterdam
Amsterdam used to be situated on the Southern sea (now-a-days "IJsselmeer"). The Amstel river was running here into the "IJ", a part of the sea, that knew tides. The canals had to be protected for these tides and also the salt water that was bad for the wooden poles on which the houses were built. Therefor locks were built. The regulated shippingtraffic, but above all the regulation of "fresh" water (see "Spuien"-customstip). The locks were then manually operated by a "sluiswachter" lockwatch. In those time a very respectable function.
"Spuien" ... a very necessary thing to keep Amsterdam inhabitable. This daily procedure was taking care of the cleaning of the canals and the refreshing of the waters. When the locks were closed, the riverwater from the Amstel was filling the canals, that got a higher and higher waterlevel. Then one opened the locks at low tide and the water flushed out, taking the larger part of the dirt out of town. Now-a-days however one does not have tides anymore and - positive - the water on the outside of A'dam is sweet. They now have a "spui" system in which the canal are cleaned as well. Partly pumping and partly accumilating-effect of water from the Amstel are the bases of the new system. However, to keep the canals clean, one has to do much more in present times.
The canals of course are one of the major attractions of the 'Venice of the North'. By daytime already very charming, by night they become even more enchanting because a lot of the canal houses and bridges are beautifully illuminated. The four main city center canals are Prinsengracht, Herengracht, Keizersgracht and Singel, and of course there are numerous smaller canals.