Note, you must be logged into your account w/ Xbox Live Gold to qualify for the offer.
PlayStation Network also has Battlefield 4 Naval Strike DLC (PS4 or PS3) for Free. Thanks rjptl96 [Discuss]
Origin also has Battlefield 4 Naval Strike DLC (PC Digital Download) for Free. Thanks peterjamesbond [Discuss]
Editor's Notes & Price Research
These add-ons require the base game in order to play. Each has a MSRP of $14.99.
NOTE: Requires Xbox Live Gold membership