The city of Venice is easily reached from Paris by train using the overnight service out of Bercy station.
If your an adventurous type, the campsite at Mistre on the mainland overlooking Venice old town is ideal and with great facilities.
It even has its own boat service to the old city. If the boat works out a bit pricey, buses from Mistre campsite take you to Mistre transport exchange, from which a five minute ride by train or bus takes you to the heart of Venice proper- couldn't be easier.
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