Suff, you'll get 'een grote klap' calling them Vikings. Part of the east of what is now the Netherlands was in Old Saxony.... you know, the mob that invaded and who, with us, turned into Anglo-Saxons. Perhaps that is why they are the most like us of all the Europeans - similar attitude to life, sense of humour, etc..
I spent seven years on the Dutch / German border and some part of all weekends in Nijmegen, Den Bosch, Eindhoven and Venlo. Summer weekends were almost exclusively on the lakes of the Maasduinen National park.
As for the the other stuff.... anyone ever caught in Amsterdam or Rotterdam when Feyenoord were playing Ajax will be able to tell you just how violent football violence really can be.