Virtual locks

The following links show how locks work (with varying degrees of success!)

Have fun!

http://www.iwr.usace.army.mil/ndc/animlock.htm

http://www.burgundy-canal.com/ulockit.html

http://www.haworth-village.org.uk/nature/how/canal-lock.asp

http://www.pancanal.com/eng/general/howitworks/como-funcion.html (with sound effects)