The $25 fare was immediately matched by Aloha Airlines and Hawaiian Airlines.

Joe Bock, a spokesman for go!, said the new fares go on sale tomorrow and are good for all seats that are available on Christmas and Christmas Eve. Passengers can purchase the $25 tickets up to the date of travel so long as the flights aren't sold out.

Unlike go!'s special, Aloha and Hawaiian said the $25 fare won't be available for all seats. But Aloha and Hawaiian said they plan to offer a significant number of seats at that price.

The move comes after go! lowered one-way fares on Sunday to $29 for interisland travel through Jan. 31. Maui-based Pacific Wings

Island Air, the state's third-largest airline, said yesterday it is offering $12 return flights for customers who buy a round-trip interisland ticket.

Meanwhile, commuter airline Pacific Wings announced that its customers will fly free on Christmas. The airline said the free flights are on a first-come, first-served basis and that passenger can begin making reservations tomorrow.

Go!, a unit of Phoenix-based Mesa Air Group, triggered a fare war when it opened for business on June 9 with an introductory $39 one-way fare.

The airline later dropped fares to $29 and $19 at various times. Aloha and Hawaiian have matched each of the discounts.