Hawaii Superferry decided to discontinue operations after the Hawaii Supreme Court ruled on Monday that the company was unfairly allowed to bypass an environmental review.
"While the appeal is not yet final because a judgment on appeal has not been entered, we want to proceed prudently and have decided to cease operations for the present," Hawaii Superferry said in a statement.
"Our first priority is to take care of our customers, both those who have recently traveled and need to return to either Oahu or Maui and those who have future bookings. We will make one additional round trip to get vehicles back to their homes this Thursday."
Superferry's opponents have argued that its ship, a 350-foot catamaran, could harm whales and other sealife. Superferry transports passengers and cars between Oahu and Maui.
In 2007, the Hawaii Legislature passed a law enabling the Superferry to operate while an environmental-impact study was done. But the state's Supreme Court on Monday said the law was unconstitutional, and sent the case back to circuit court.
Superferry said it began layoffs March 20. The company employs 161 full-time and part-time employees and 75 contracted employees.