Cruise Carnival extends group booking promotion By Tom Stieghorst / August 26, 2013 Share 1 -- Carnival Cruise Lines said it would extend by a month its August group booking promotion. It also lengthened the booking window so that after Sept. 1, the promotion applies to cruises taken through Dec. 31, 2014, rather than the previous date of May 31. Carnival is offering one free cruise berth for every 10 full-fare tickets sold, compared with one for every 15 previously. Group fares applicable to this promotion begin at $199 for three- to five-day cruises and $449 for cruises of six days or longer. Carnival will continue to open its Group Contact Center on the weekend from 10 a.m. to 4 p.m through the end of September. Follow Tom Stieghorst on Twitter @tstravelweekly.