O'ahu residents snapped up $5 fares for the Hawaii Superferry yesterday, which will make its inaugural cruise to Maui this morning. More than 90 percent of all discounted tickets offered through Sept. 5 were sold, despite the threat of an injunction that could stop service.

"The response has just been tremendous," Superferry director of business development Terry O'Halloran said.

Superferry officials said today's initial trip from O'ahu to Maui sold out within 30 minutes of going on sale at 6:30 a.m. Throughout yesterday, more than 19,000 seats were sold for $5. Of the 42 trips with discounted tickets through Sept. 5, about half are already sold out.

The ferry will take 500 passengers and 150 cars per trip.

Superferry announced the special fares Friday — while also saying the service would launch two days earlier than planned — after a legal setback from the state Supreme Court.

In an opinion issued Thursday, the court said the company must conduct an environmental assessment of its operation. But the court did not spell out whether the assessment could be done while service is in operation.

Environmentalists who pushed for the review will ask for an injunction against the ferry tomorrow. If approved, the injunction could postpone the service for months.

So far, ferry officials have been unable to say whether a court action could strand some passengers on Kaua'i or Maui if they bring their vehicles with them.

"I'm not going to speculate on any court proceedings," O'Halloran said. "We're beginning service ... and looking forward to carrying people between the islands."

DOT: NO INTERRUPTION

For its part, the state Department of Transportation has said the Superferry should be able to offer service while the environmental assessment is being completed.

"The court did not specifically specify that they could not commence operations," said DOT Director Barry Fukunaga in a news conference on Friday.

Environmentalists and Neighbor Islanders who are seeking the injunction were tentatively planning picket lines and sign waving on Kaua'i today. Nothing was planned for Maui.

At the least, said Maui Tomorrow spokesman Ron Sturtz, opponents will be watching the arrival closely.

The Superferry was docked at Kawaihae Harbor on the Big Island through much of yesterday for an open house.

O'Halloran said more than 2,000 people walked through the ship, adding to the 20,000 people who have toured the Superferry in similar events and free cruises on other islands. The Superferry is due to start service to Kawaihae in 2009, and launches daily back-and-forth trips to Kahului and Nawiliwili from Honolulu today.

Regular one-way adult prices for service to Maui or Kaua'i run from $44 to $62, plus fuel surcharges of $10 to $19. One-way fare for a vehicle costs about $50, not including additional fuel surcharges and taxes.

The popularity of the $5 fare overwhelmed the Superferry reservation desk, leaving some callers with long waits. At about 4 p.m. yesterday, three hours before the reservation desk closed, the wait time was 30 minutes.

GLITCHES ANNOY SOME

P.J. O'Reilley, of Punchbowl, bought a ticket for today's cruise shortly after 6:30 a.m. But then he realized he had another obligation and that's where the trouble began.

He said when he tried to cancel the reservation, he kept getting a busy signal. He tried to cancel it online but found out he couldn't. Then, he went down to the Superferry offices, and was told to call the reservations desk.

"This is a not ready for prime time operation," he said.

But others were excited about getting a cheap getaway.

Heather Crislip, of Nu'uanu, bought $5 Superferry tickets to Maui for her family of three yesterday morning.

She'll sail next weekend, with her car, and spend two days on Maui before heading home. "I thought it would be fun to take advantage of," she said, laughing.

She added that even without the cheap fares, her family was excited about trying the ferry — just not right away.

"We would have gone eventually," she said.

Reach Mary Vorsino at mvorsino@honoluluadvertiser.com.