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Three years after a Princess Cruise Lines engineer discovered a "magic pipe" used to illegally dump oil-contaminated waste into the water and notified authorities, Princess is paying a $40 million fine and apologizing for the damage done.

The cruise line pleaded guilty to seven federal charges, and its parent company, Carnival, will also have to put 78 ships through a five-year environmental compliance program. U.S. Attorney Wifredo Ferrer called it the largest penalty of its kind. "Our open seas are not dumping grounds for waste," he said. "One thing we must never do is take our clear blue oceans for granted." Princess said it was "extremely disappointed" that the law was violated. If the plea deal is approved by a federal judge, $14 million of it will be used for environmental projects in Florida, Britain, and international open waters.

The waste comes from the engines and fuel systems of ships, and it's supposed to be offloaded when in port. From there, it is either burned in an incinerator or properly disposed at a waste facility. In some cases, if most of the oil is separated out, the waste can be diverted into the ocean. After the engineer came forward in 2013 with information on illegal dumping on the Caribbean Princess, investigators discovered that other Princess ships had been illegally discharging the oily water into the ocean since 2005, The Associated Press reports. Court documents show that during one dump, 4,227 gallons of oily waste was discharged into the water 20 miles off the coast of England. Authorities say this was done to save money, and officers and crew members were in on it.