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.