MIAMI – Princess Cruise Lines has agreed to pay a $40 million penalty and plead guilty to seven federal charges in an illegal ocean pollution case.

Miami U.S. Attorney Wifredo Ferrer told reporters Thursday that the penalty is the largest ever of its kind. The plea agreement filed in federal court also requires Princess and its parent company, Carnival Corp., to submit all cruise ships to a five-year environmental compliance program overseen by a judge.

Court documents show one Princess ship was illegally discharging oily waste from 2005 to 2013 until a whistleblower engineer informed authorities. One method used to bypass proper procedures was a “magic pipe” that diverted oily water into the ocean.

Documents show illegal practices were found on four other Princess ships. Authorities say cost savings was the motive.