If the weather is fine, take the train to Maassluis where you can hire a bicycle from the station for EU5 for the day. Then cross the ferry to Rozenburg and cycle down the narrow spit of land between the New Waterway and the Caland Canal. This way you will see large numbers of tankers and bulkers in the Caland Canal plus everything on the New Waterway. No shops or facilities on this route - so take food with you. If nice weather, the best possible way of seeing large numbers of vessels.
Piet B