"Head to the Jersey Coast for a sunny afternoon of boardwalk-based Multiplayer battle in which you'll face your enemies on the beach and fight for dominance at the arcade while still finding time to cut the line at the rollercoaster." - Official Description on the Call of Duty: Elite Content Calendar

Boardwalk is available for purchase as part of Collection Pack 4 for Modern Warfare 3.

(writeup coming soon)

Screenshots from the Call of Duty wikia page for Boardwalk and CallOfDutyMaps.com.