Carnival Cruise Lines (Carnival) launched in March 1972. Headquartered in Miami, Florida, Carnival is a subsidiary of Carnival Corporation, which controls almost 50 percent of the worldwide cruise ship market. Carnival has now surpassed Royal Caribbean with the largest number of cruise ships -- 24 -- in a single fleet, and all but one (Carnival Ecstasy) of its 24 ships with carrying capacities of 3,500 or more passengers and crew. Slightly less than half of Carnival’s ships were built in the last decade, with 12 of those ships having a carrying capacity of 4,400 or more passengers and crew.

Of Carnival’s 24 ships, only two -- the Carnival Spirit, which operates in Alaska, and Carnival Dream -- have installed advanced sewage treatment systems, resulting in a grade of F for the company’s 8 percent sewage treatment score. In determining the air pollution reduction grade for each cruise line, only ships that dock at a port that currently has shoreside power (thereby avoiding burning dirty fuel in port) were considered. Carnival made a commitment in their 2009 Sustainability Report to install shoreside power capability to all ships that will home port at the Port of Long Beach by 2014. In total, 50 percent of Carnival’s ships that dock at a port with shoreside power are plug-in capable, giving the company a C- in this category. In 2010, the Carnival Spirit, Carnival’s sole cruise ship operating in Alaska, received three citations from Alaskan authorities for violations of Alaskan water pollution standards, giving Carnival a B+ for water quality compliance in Alaska.