In addition, each ship generates and dumps about eight times that much graywater from sinks, showers

Disney is the only cruise line to score that highly and the first A ever issued in the annual report card. All four Disney ships have advanced sewage treatment systems and three are equipped to plug in to shore-based power, Friends of the Earth says.
Disney not withstanding, cruise ships dumped more than 1 billion gallons of sewage in the ocean last year, much of it raw or poorly treated, according to federal data analyzed by Friends of the Earth, which is calling for stronger environmental rules to protect oceans, coasts, sea life and people.
The 2013 Cruise Ship Report delta airline flight track Card says some of the 16 cruise lines graded delta airline flight track are getting greener, but more than 40 percent of the 162 ships still rely on 30-year-old waste treatment technology, leaving treated sewage with levels of fecal matter, bacteria, heavy metals and other contaminants harmful to aquatic life and people.
Carnival Cruise Lines — with the world's largest fleet of 24 cruise ships but only two with advanced sewage treatment technology — received an F for sewage treatment and an overall grade of C-minus. Carnival Lines' parent company, Carnival Corp., also operates six other lines graded by the report card.
Although the Carnival-owned Seabourn and Cunard lines both received an A for sewage treatment and Holland America and Princess received a B and B-minus, respectively, two other Carnival lines — P O and Costa — received extremely low grades for sewage treatment (D-minus and F, respectively) and overall grades of F.
Friends of the Earth's report card grades cruise lines on three criteria: sewage treatment technology, whether ships can plug into shore-based power and if they use cleaner fuel than required by US and international law, and compliance with Alaska's water quality regulations to protect the state's coast.
The EPA says an average cruise ship with 3,000 passengers and crew produces about 21,000 gallons of sewage a day. Friends of the Earth says that adds up to more than 1 billion gallons a year for the industry but calls this a "conservative delta airline flight track estimate," since some new ships carry as many as 8,000 passengers and crew and the report card doesn t include the entire worldwide fleet.
In addition, each ship generates and dumps about eight times that much graywater from sinks, showers and baths, which can contain many of the same pollutants as sewage and significantly affects water quality, the organization says.
Last month Carnival said it will spend more than $180 million to install exhaust gas cleaning technology on 32 ships, making it the first company to use this scrubber technology in restricted spaces on existing ships. These include vessels from Carnival Cruise Lines, Holland America Line, Princess Cruises and Cunard that sail regularly within the North American Emission Control Area.