You must carry onboard:
A copy of the current inland waterways rules (Binnenvaart Politie Reglement (BPR) which is published in volume 1 of the ANWB Wateralmanak (only available in Dutch).

Certificate of competence:
On Dutch inland waters the skipper of a vessel over 15m in length or capable of more than 11 knots must have an ICC

Entry from a non-Schengen country:
A border free agreement, known as the Schengen Agreement, exists between 15 countries (Austria, Belgium, Denmark, Finland, France, Germany, Iceland, Greece, Luxembourg, Netherlands, Norway, Portugal, Spain and Sweden). A crew list form must be completed for any vessel entering the Netherlands from outside these countries. The form and a document detailing your obligations are available to download.

Other:
Whilst visiting the Dutch inland waters ensure that the compulsory listening watch is maintained on the specified VHF channel (see the ANWB Wateralmanak or local charts).

The Netherlands is introducing regulations on the discharge of black water. From January 2009 it is prohibited to discharge black water (toilet waste) from all pleasure boats on all inland waterways, lakes, the Waddensea and territorial waters. Pleasure boats can be installed with holding tanks, dry or chemical toilets or boaters could choose simply not to use their toilets. Further information is available at:
www.vuilwater.info/brochures and www.vuilwater.info/vertaling