Spido harbour trip, Willemsplein 85, ☎ +31 (10) 275 99 88 (spido@spido.nl, fax: +31 (10) 412 47 88), [63]. You only see the first 8 km of the harbor starting at the Erasmus bridge (the trip doesn't go all the way to the north sea, and skips some of the more interesting harbors) But Rotterdam is REALLY big, so even in those first 8 km there's plenty to see.
