Norwegian Cruise Line and Pepsi have teamed up for an unusual summer promotion that will bring free soda to passengers.

In an announcement Monday, the line said customers who book a seven-night or longer cruise before Oct. 15 for sailings through 2010 are eligible for the offer. The cruisers (up to two per cabin) must sign up for the Pepsi Summer Cup promotion at the time of booking by referencing promotion code PGPOP.

Once on board, passengers who have signed up for the offer will get a special Norwegian and Pepsi branded souvenir cup that gives them access to unlimited fountain soda refills at any bar, lounge or restaurant throughout their cruise. Soda options include Pepsi, Diet Pepsi, Mountain Dew and Sierra Mist.

Free soda on a mass-market cruise line? Yes, but only for a ...