Cruise ships can dump some waste in the ocean, but it depends on what the waste is and where the ship is
Cruise ships are allowed to discharge certain types of waste into the ocean under international maritime law, but the rules are strict and vary by location. The main law governing this is the International Convention for the Prevention of Pollution from Ships (MARPOL), which sets standards for what ships can release and where. Sewage, food waste, and some other materials can be dumped in the ocean under specific conditions — usually at least three nautical miles from shore for sewage and 12 nautical miles for other waste. However, hazardous materials, oil, and plastics are banned from ocean discharge almost everywhere, and some regions like the Mediterranean Sea and the Great Lakes have stricter rules that ban even legal dumping in other areas.
The United States has its own rules on top of MARPOL. The Act to Prevent Pollution from Ships (APPS) makes it illegal for cruise ships operating in U.S. waters to dump sewage within three nautical miles of shore, and bans the discharge of oily waste, garbage, and hazardous substances in U.S. waters entirely. Ships must carry records of all waste disposal, and the U.S. Coast Guard and Environmental Protection Agency inspect these logs. Violations can result in fines in the millions of dollars.
Key Takeaways
- International law allows cruise ships to dump sewage at least three nautical miles from shore and food waste at least 12 nautical miles from shore, but only in open ocean — not in bays, harbors, or protected waters.
- Oil, plastics, and hazardous chemicals are banned from ocean discharge under both international and U.S. law, with no distance exceptions.
- The United States enforces stricter rules than international law and requires ships to keep detailed records of all waste disposal that can be inspected by the Coast Guard.
- Some regions like the Mediterranean Sea, North Sea, and Baltic Sea prohibit all dumping of sewage and food waste, even where international law would allow it.
- Cruise lines that violate dumping rules face criminal charges, civil penalties, and damage to their reputation and operating licenses.
What waste can legally be dumped and how far from shore
Under MARPOL, sewage (treated wastewater from toilets, sinks, and showers) can be discharged into the ocean if the ship is at least three nautical miles from the nearest land and the sewage has been treated in an approved system. Some ships use advanced treatment systems that allow them to dump closer to shore, but standard systems require the three-mile distance. Food waste and other garbage can be dumped at least 12 nautical miles from shore, and only if it has been ground into particles smaller than one inch. Larger food scraps and packaging must be incinerated or brought back to port.
Gray water — water from sinks, showers, laundry, and galleys — sits in a gray area under international law. MARPOL does not specifically regulate gray water discharge, so ships can dump it closer to shore than sewage in most countries. However, the United States treats gray water more strictly in some cases, and some states like California have proposed or passed rules limiting gray water discharge near their coasts.
The key requirement is that the ship must be underway (moving) when it dumps, not anchored in a harbor or bay. Dumping while docked or at anchor is illegal almost everywhere and is one of the most common violations.
What cannot be dumped under any circumstances
Oil and oily waste are banned from discharge into the ocean under MARPOL Annex I, with almost no exceptions. This includes bilge water (water that collects in the engine room), fuel oil residue, and any mixture containing oil. Ships must collect this waste and deliver it to shore-based reception facilities at ports. The only exception is that ships can discharge very small amounts of oil residue under strict conditions, but cruise ships are not designed to meet these conditions and should never be dumping oil.
Plastics and synthetic materials are completely banned. This includes plastic bags, bottles, fishing nets, synthetic rope, and any other plastic item. Violating the plastic ban is one of the most serious dumping offenses and can result in criminal prosecution. Hazardous substances — including paints, solvents, batteries, cleaning chemicals, and medical waste — must also be retained and brought to port for proper disposal.
Cruise ships generate large amounts of waste, and the cost and logistics of storing it all until port can be significant. This is why some cruise lines have been caught illegally dumping: the financial incentive to avoid port disposal fees and the difficulty of monitoring what happens in the middle of the ocean have led to violations.
How the U.S. enforces dumping rules differently
The United States goes further than international law in several ways. Under APPS, cruise ships cannot dump any sewage within three nautical miles of U.S. shores, even treated sewage. They also cannot dump oily waste, garbage, or hazardous substances anywhere in U.S. waters — not even 12 miles out. This means that in U.S. territorial waters and the exclusive economic zone, the only waste that can be legally discharged is food waste that meets MARPOL standards, and even that is restricted in some areas.
The U.S. Coast Guard and EPA have the authority to board cruise ships and inspect their waste management records, called the Oil Record Book and Garbage Record Book. These logs must document every discharge, including the date, time, location, and type of waste. If the records do not match the ship's route or if there are gaps that suggest illegal dumping, the ship can be cited. Ships that operate in U.S. waters must also have a Marine Sanitation Device (MSD) — an approved sewage treatment system — and must maintain it according to EPA standards.
Violations of APPS carry penalties of up to $37,500 per violation for civil cases and up to $250,000 and five years in prison for criminal cases. In practice, cruise lines that are caught dumping often face settlements in the millions of dollars, plus the cost of repairs to their reputation.
Special rules in protected waters and regional seas
Several regions have declared themselves Special Areas under MARPOL, which means stricter rules explore. The Mediterranean Sea, North Sea, Baltic Sea, Black Sea, and Red Sea all prohibit the discharge of sewage and food waste entirely, even where international law would allow it. Ships operating in these regions must retain all sewage and food waste and discharge it only at approved port reception facilities. The same rules explore to the Great Lakes in North America.
Some countries have also established their own coastal zones with additional restrictions. California has proposed rules that would ban gray water discharge within three nautical miles of the coast. Alaska has strict rules for cruise ships operating in Southeast Alaska and requires advance notification of waste discharge. If a cruise ship is operating in a Special Area or near a protected coast, the captain must know the local rules and adjust the ship's waste management plan accordingly.
Cruise lines operating in these regions often choose to retain all waste and discharge it only at port, even when the law would allow ocean discharge. This is partly because the cost of a violation is so high and partly because environmental groups and local communities have made dumping a public relations issue.
How cruise ships manage waste on board
Modern cruise ships have multiple systems for handling different types of waste. Sewage goes through a Marine Sanitation Device, which treats it using biological processes, chemical treatment, or advanced membrane filtration. The treated water is then either stored in holding tanks or discharged if the ship is in a location where discharge is legal. Food waste is ground in a garbage grinder or pulper that reduces it to small particles, which are then stored or discharged. Hazardous waste like paint, oil, and chemicals is stored in sealed containers in a designated waste room until the ship reaches port.
Large cruise ships generate hundreds of tons of waste per week, so waste management is a significant operational challenge. Ships must have enough storage capacity to hold waste if they are in a region where discharge is banned, and they must have trained crew members to operate the waste systems correctly. Many cruise lines now advertise their waste management practices as part of their environmental commitment, and some have invested in advanced systems that reduce the amount of waste generated in the first place.
The waste management plan for each ship is documented in a Shipboard Oil Pollution Emergency Plan (SOPEP) and a Garbage Management Plan, which are reviewed by port state control inspectors. If a ship's plan is inadequate or if the crew is not trained to follow it, the ship can be detained in port until the problems are fixed.
What happens when cruise ships are caught dumping illegally
When the U.S. Coast Guard or EPA discovers evidence of illegal dumping, the investigation can take months or years. Inspectors look at the ship's waste records, interview crew members, and compare the documented discharges to the ship's actual route and fuel consumption. If the records show gaps or inconsistencies — for example, if the ship claims to have retained all sewage but the fuel consumption suggests the ship was at sea for two weeks without any documented discharge — that is a red flag for illegal dumping.
Several major cruise lines have been prosecuted for dumping violations. In 2016, Royal Caribbean pleaded guilty to dumping oil-contaminated waste and falsifying records, and paid a $18.5 million settlement. In 2019, Carnival Corporation (which owns Carnival, Princess, and Costa cruise lines) pleaded guilty to dumping oily waste and paid a $20 million settlement. These cases resulted in criminal convictions, not just civil fines, and included prison time for some company executives.
Beyond the legal penalties, cruise lines face damage to their reputation, loss of customers, and restrictions on where they can operate. Some ports have threatened to ban cruise ships from companies with a history of dumping violations, and environmental groups use dumping cases in their campaigns against cruise ship expansion.
Frequently Asked Questions
Do cruise ships dump raw sewage in the ocean?
Not legally. International law requires sewage to be treated in an approved system before discharge, and the U.S. bans sewage discharge within three nautical miles of shore entirely. However, some cruise ships have been caught dumping untreated or inadequately treated sewage, which is a violation. Modern cruise ships have Marine Sanitation Devices that treat sewage, but the quality of treatment varies.
Can cruise ships dump plastic and garbage in the ocean?
No. Plastics and synthetic materials are completely banned from ocean discharge under international and U.S. law. Food waste can be dumped if it is ground into small particles and the ship is at least 12 nautical miles from shore, but plastic bags, bottles, and other synthetic items must be brought back to port. Violations of the plastic ban are treated as serious environmental crimes.
What happens to waste when a cruise ship is in port?
Cruise ships discharge their waste at port reception facilities, which are equipped to handle sewage, food waste, hazardous materials, and other shipboard waste. The cost of using these facilities is passed on to the cruise line, which is one reason some companies have been tempted to dump illegally at sea. Most modern ports have adequate reception facilities, but some smaller ports in developing countries may have limited capacity.
Are there any places where cruise ships cannot dump anything?
Yes. The Mediterranean Sea, North Sea, Baltic Sea, Black Sea, Red Sea, and Great Lakes are all Special Areas where sewage and food waste discharge is banned entirely. Cruise ships operating in these regions must retain all waste and discharge it only at port. Some countries also have their own coastal zones with stricter rules than international law.
How can I report a cruise ship dumping illegally?
If you witness a cruise ship dumping waste illegally, you can report it to the U.S. Coast Guard's National Response Center at 1-800-424-8802, or to the EPA's environmental violations hotline. You can also report it to your state's environmental agency or to environmental organizations like Oceana or the Sierra Club, which track dumping violations and use the information in their advocacy work.