On the Zaandam you may smoke in your cabin and on your balcony. There is a smoking section in the Ocean Bar and the Casino bar. The Crows Nest lounge has the largest smoking section available inside.
Outside you may smoke anywhere you like. There are ashtrays on the rails at various points on the outside decks for your use.
The casino is smoking but may have one or two non smoking nights as well, if they do then the casino bar will also be non smoking on those nights. This is the current policy but may change without notice.