Newly released government evidence tapes from 1993 show a 7-mile-long oil slick from a ship on route to Miami

MIAMI (CNN) -- Royal Caribbean International will pay a $9-million fine for dumping oil into the Caribbean and Atlantic oceans, the highest pollution fine ever assessed against a cruise company.

The U.S. Justice Department said the cruise line continued its practices of dumping oil into the oceans even after pleading guilty to polluting and then trying to cover up its actions.

"They show just how hard it is to change a corporate culture which tolerated pollution and fell asleep at the mast," said Richard Udell of the Justice Department.

On Wednesday, a U.S. judge in Miami ordered Royal Caribbean to pay a $1 million fine, part of a plea-bargain agreement reached last June that will have the company paying a total of $9 million.

"It's a substantial mount of money," said Assistant U.S. Attorney Tom Watts-Fitzgerald. "This is the largest collective fine in the cruise ship industry. That alone has to send a significant message."

The millions of dollars in fines will help repair coral reefs. Along with the fine, U.S. District Judge Donald Middlebrooks put the cruise line on five years probation and ordered it to submit an environmental compliance plan by December 15.

In a pretrial agreement with prosecutors, Royal Caribbean pleaded guilty in June to eight felony counts in cases brought in Puerto Rico and Florida. Sentencing in the Puerto Rico case, in which Royal Caribbean agreed to pay $8 million, is set for September 25.

Justice department prosecutors say these pictures show an extra pipe appearing and disappearing, a design intended to circumvent pollution controls

Newly released government tapes show the cruise line's practice of dumping oil into the oceans goes back to 1993.

On one tape, infrared cameras captured a seven-mile (11-kilometer) oil slick left by a Royal Caribbean ship. The cruise line's Nordic Empress pumped bilge waste into the Atlantic on its way from the Bahamas to Miami on February 1, 1993. A U.S. Coast Guard aircraft searching for drug smugglers spotted the oil slick.

When the ship docked in Miami, U.S. authorities asked to see a log in which ship's officers were required to record bilge pumping. The log falsely omitted the fact that the ship had pumped oily waste into the water, said Watts-Fitzgerald.

Other tapes show that in 1994, Royal Caribbean's Sovereign of the Seas ship left plumes of oil off the coast of Puerto Rico, and in 1995, the Monarch of the Seas disgorged more oil, which trailed in the ship's wake for 22 miles (35 kilometers).

The government also released a tape showing an extra pipe appearing and disappearing on a ship, which the Justice Department said proves that Royal Caribbean crews installed systems meant to circumvent required pollution controls to save the cost of proper disposal. The government said crews dismantled the systems before inspectors arrived.

Royal Caribbean admitted in June that ship's crews routinely pumped oil bilge and kept dummy logs that the crews called "fairy tale" books. The company also admitted to disassembling illegal sewage pipes bypassing cleaning devices as part of an attempt to hide the illegal practices.

"These acts were inexcusable. They were wrong. They should not have happened," said Jack Williams, president of Royal Caribbean.

The investigation into Royal Caribbean's environmental practices has not ended, said Watts-Fitzgerald.

CNN Correspondent Susan Candiotti and Reuters Limited contributed to this report.