MS Westerdam is a Vista-class cruise ship owned by Holland America Line. She is the third ship of the class to be operated by the line, as well as being the third ship to bear the name Westerdam. Her sister ships are Oosterdam, Zuiderdam, and Noordam. The beginning of the four ships' names represent the four directions of the compass in Dutch.

The Vista class is a class of Panamax-type cruise ships, built by Fincantieri Marghera shipyard, in Italy. Vista-class cruise ships are operated by Holland America Line, P&O Cruises, Cunard Line, Costa Cruises, and Carnival Cruise Line. The ships are equipped with a diesel-electric power plant and an Azipod propulsion system. The ships are designed so that eighty-five percent of the staterooms have ocean views and sixty-seven percent have verandas; the extensive use of glass in the superstructure of Vista-class ships is also reflected in the class name.