While interisland airfares are going up, the Hawaii Superferry is keeping its prices down.

The Superferry said yesterday it is extending its promotional $39 one-way passenger fare and $55 vehicle charge until June 5. It originally planned to end the discounts on March 12.

Also yesterday, the Superferry said it will add a second voyage between Maui and O'ahu starting Jan. 16 to boost ridership and cater to growing interest among business and other customers.

News of a second Maui trip was not welcomed by all. The Maui mayor expressed concern about the impact on traffic, and the head of an environmental group said extending ferry hours into the night could endanger whales.

The Superferry had planned a second daily Maui run next year after it added another ship. Ferry executives accelerated the plan since the Superferry is not yet serving Kaua'i.

"As we have always stated, our business model is dependent on running two trips per day and right now we've got to meet those needs," said John Garibaldi, president and CEO of Hawaii Superferry in a prepared statement.

"Providing service to Kaua'i is very important to us. We recognize and appreciate the strong support from many in the community," Garibaldi said. "We've decided, however, to initiate a second voyage to Maui sooner in order to allow more time in which to work with the community on Kaua'i to ensure a safe and successful resumption of service."

Terry Halloran, director of business development for Hawaii Superferry, estimated the vessel has been averaging about 200 passengers per trip since the ferry resumed service on Dec. 13. The vessel has a capacity of 866 passengers and 282 vehicles.

"We're pleased with the early response," Halloran said. He said the loads are increasing, customer response has been "very positive," with a good deal of commercial interest in the second voyage.

"This provides an opportunity for us to really bring a higher level of service to both Maui and O'ahu and connect those two islands," he said.

EARLY TROUBLES

The company initially started service with its ship the Alakai in late August but was halted by legal challenges on Maui and protests on Kaua'i. In October the company laid off 249 of its 308 employees after saying it was losing $650,000 per week.

The Superferry resumed Maui service Dec. 13, but has not set a date to restart service to Kaua'i,

The Superferry announcement of a second daily Maui trip raises concerns the 349-foot vessel will strike humpback whales while it travels through the whale sanctuary at night, said Irene Bowie, executive director of Maui Tomorrow.

The two spotters placed on the Superferry to avoid whales will not be effective at night at the speeds the Superferry travels, even if the spotters use night vision equipment as the company has proposed, Bowie said.

"I think it's a real issue for them to be traveling at 25 knots through sanctuary waters after dark," Bowie said.

Maui Tomorrow is one of three plaintiffs that went to court to try to force the state Department of Transportation to complete an environmental impact statement on the Superferry before the vessel began operations.

Bowie also noted that the environmental report on the Superferry operation has not been completed, and said the Superferry has done little to reach out to the Maui residents who are concerned about the operation.

"I guess I'm skeptical that they feel any need to talk to any of us," she said. "It doubles the impact on Maui while the environmental review is still in process. To do this while the EIS is incomplete seems not wise."

'VERY DISAPPOINTED'

Maui Mayor Charmaine Tavares said, "I am very disappointed that Hawaii Superferry has made this decision without consulting county officials and members of our community. Just weeks ago I received a commitment from Mr. Garibaldi that the company would extend its efforts to work with us, but their announcement comes as a surprise."

Tavares expressed concern about the lack of a study on how the ferry will affect traffic. "Now there will be two daily trips, and still no traffic study," she said.

Halloran said the Superferry business plan always included a second daily trip to Maui, "so we just decided we're going to move that timetable up and offer the two trips between Maui and O'ahu now so that we really can fully develop this market segment."

Halloran predicted ridership will climb, particularly with the extending of the promotional fares.

"We feel like we're definitely going to pick up volume with that pricing," he said.

The second voyage will operate Sunday through Friday, leaving Honolulu at 3:15 p.m. and arriving in Kahului at 7. It will depart from Kahului at 8 p.m. and arrive in Honolulu at 11. The first daily voyage will continue its regular daily schedule.

Tickets for the promotional fares must be purchased by March 31. Reservations can be made through www.HawaiiSuperferry.com or through the call center at 877-HI-FERRY (877-443-3779).

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.