<P> This article describes the several types of waste streams that cruise ships may discharge and emit . It identifies the complex body of international and domestic laws that address pollution from cruise ships . It then describes federal and state legislative activity concerning cruise ships in Alaskan waters and activities in a few other states, as well as current industry initiatives to manage cruise ship pollution . </P> <P> More than 46,000 commercial vessels--tankers, bulk carriers, container ships, barges, and passenger ships--travel the oceans and other waters of the world, carrying cargo and passengers for commerce, transport, and recreation . Their activities are regulated and scrutinized in a number of respects by international protocols and U.S. domestic laws, including those designed to protect against discharges of pollutants that could harm marine resources, other parts of the ambient environment, and human health . However, there are overlaps of some requirements, gaps in other areas, geographic differences in jurisdiction based on differing definitions, and questions about the adequacy of enforcement . </P> <P> Public attention to the environmental impacts of the maritime industry has been especially focused on the cruise industry, in part because its ships are highly visible and in part because of the industry's desire to promote a positive image . It represents a relatively small fraction of the entire shipping industry worldwide . As of January 2008, passenger ships (which include cruise ships and ferries) composed about 12% of the world shipping fleet . The cruise industry is a significant and growing contributor to the U.S. economy, providing more than $32 billion in total benefits annually and generating more than 330,000 U.S. jobs, but also making the environmental impacts of its activities an issue to many . Since 1980, the average annual growth rate in the number of cruise passengers worldwide has been 8.4%, and in 2005, cruises hosted an estimated 11.5 million passengers . Cruises are especially popular in the United States . In 2005, U.S. ports handled 8.6 million cruise embarcations (75% of global passengers), 6.3% more than in 2004 . The worldwide cruise ship fleet consists of more than 230 ships, and the majority are foreign - flagged, with Liberia and Panama being the most popular flag countries . Foreign - flag cruise vessels owned by six companies account for nearly 95% of passenger ships operating in U.S. waters . Each year, the industry adds new ships to the total fleet, vessels that are bigger, more elaborate and luxurious, and that carry larger numbers of passengers and crew . Over the past two decades, the average ship size has been increasing at the rate of roughly 90 feet (27 m) every five years . The average ship entering the market from 2008 to 2011 will be more than 1,050 feet (320 m) long and will weigh more than 130,000 tons . </P> <P> To the cruise ship industry, a key issue is demonstrating to the public that cruising is safe and healthy for passengers and the tourist communities that are visited by their ships . Cruise ships carrying several thousand passengers and crew have been compared to "floating cities," in part because the volume of wastes produced and requiring disposal is greater than that of many small cities on land . During a typical one - week voyage, a large cruise ship (with 3,000 passengers and crew) is estimated to generate 210,000 US gallons (790,000 L) of sewage; 1 million US gallons (3,800 m) of graywater (wastewater from sinks, showers, and laundries); more than 130 US gallons (490 L) of hazardous wastes; 8 tons of solid waste; and 25,000 US gallons (95 m) of oily bilge water . Passengers can, singlehandedl, produce up to 7.7 pounds of waste in a single day aboard a cruise ship . Those wastes, if not properly treated and disposed of, can pose risks to human health, welfare, and the environment . Environmental advocates have raised concerns about the adequacy of existing laws for managing these wastes, and suggest that enforcement of existing laws is weak . </P>

Where does the trash go on a cruise ship