Direct service from Rotterdam Centraal via Vlaardigen about 20 minutes.
Walk. Its good for you.
The Steam Boat museum. On Hoogstraat (High street) cost : 4 Euro. You get to see the last sea-going steam powered tug the "Furie".
Grote Kerk that towers above the town. 17th Century church open to the public on Wednesday afternoons 14:00 - 16:00 during the months of June, July, August and September. Website http://www.pknmaassluis.nl/grootekerk
Resturants abound in the central section of the city.
Try De Zoete Inval (Tea Room) on Dr Kuyperkade 15. Nice scones, coffee and tea.
There are few options. The two hotels here are part-time and you can only check in well into the afternoon.
Pension Hotel Piet-hein -Piet Heinstraat 23, 3143 AK Maassluis, Netherlands
+31 10 591 6929. Minimal services. Near the train platform but out of the Centrum.
Kreta Hotel- above the Greek resturaunt of the same name. More like a hostel than a hotel. In the Centrum, near the Sheepvart Museum on Hoogstraat Wip 1 + 31 10 591 2325
Next stop on the rail line is Hook van Holland. With access to the Stena Ferry to Harwich England. Maasland is a historic village at a distance of 2.4 km NW in the polder nearby. You can walk there: follow Noordvliet Noordzijde.