Two environmentalists and a fisherman want to postpone a hearing on Carnival Corp's probation for environmental misdeeds so they can have their voices heard.

A federal judge on 3 June plans to decide whether or not to revoke the five-year trial period, given December 2016 for eight years of illegal oil dumping and lying to US authorities.

Bahamian ecologists Fotini Tsavousis-Duncombe and Theodore Thoma and Alaskan fisherman Eric Forrer have asked to delay the hearing to June 17.

Their attorney, Knoll Lowney of Smith & Lowney, today filed an "an emergency motion to intervene" under the Crime Victim Rights' Act in southern Florida's federal court.

They want the extra time to read Carnival's record of wrongdoing and a proposed joint resolution between Carnival and the government on a motion to revoke probation.

They also want to speak with the government's attorneys and submit testimony before a decision is made, court documents state.

US District Judge Patricia Seitz has summoned Carnival executives, including chairman Micky Arison and chief executive Arnold Donald, to the 3 June hearing and has threatened to temporarily ban Carnival from docking at US ports.

An email to Carnival was not immediately returned.

'A massive amount of trash'

"On a daily basis, I saw the cruise ship industry and the ships owned by Carnival Corporation themselves violate the letter and spirit of environmental law," Forrer, who has fished the waters off Juneau for 40 years, wrote in his initial testimony.

"Over the last 30 years this has included dumping gray and black water in inside passages and offshore waters."

Tsavousis-Duncombe, co-founder of environmental group ReEarth, said she has seen countless instances of Carnival polluting the Bahamas and often wonders how severely it must impact marine wildlife.

"For example, when I was vacationing on Harbor Island, I observed a massive amount of trash that was released from one of the cruise ships covering the beach where I was walking," she wrote in her testimony.

"It was extremely distressing to see that pollution on the beach."

Carnival appears to have this attitude that US law does not apply to them because they fly under a flag of convenience, wrote Thoma, president of Responsible Cruising in Alaska.

"It is not wrong to conclude that Carnival is basically a rogue entity that simply doesn't harbor a core value related to protecting the very environment that their customers desire to see and experience while cruising," he said.

Thoma suggested any fine imposed on Carnival go to several environmental entities, including the National Park Service.

Violating probation

In 2018, Carnival acknowledged a court-appointed monitor's report saying it prepared ships before audits, falsified records and threw plastic garbage overboard.

It also admitted to dumping gray water into Alaska's Glacier Bay National Park and trying to lobby the US Coast Guard to change a related $40m fine, according to court documents.

US-based environmental group Stand.earth said it fully supports the victims’ proposed intervention on the hearing to revoke probation.

"They have a right to be heard, as a means to add transparency to this process, and to ensure that there is adequate punishment for Carnival’s crimes," the organisation said in a statement.