<P> In 2000, the U.S. Congress enacted legislation restricting cruise ship discharges in U.S. navigable waters within the state of Alaska . California, and Maine have enacted state - specific laws concerning cruise ship pollution, and a few other states have entered into voluntary agreements with industry to address management of cruise ship discharges . Meanwhile, the cruise industry has voluntarily undertaken initiatives to improve pollution prevention, by adopting waste management guidelines and procedures and researching new technologies . Concerns about cruise ship pollution raise issues for Congress in three broad areas: adequacy of laws and regulations, research needs, and oversight and enforcement of existing requirements . Legislation to regulate cruise ship discharges of sewage, graywater, and bilge water nationally was introduced in the 109th Congress, but there was no further congressional action . </P> <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>

Where does human waste on a cruise ship go