Visiting multiple islands in the Hawaiian chain is about to become much easier. A high-speed ferry will start daily trips July 1 and will be joined by a sister ship in 2009.

That means travelers won't have to put up with agonizing waits at airports or the need to book car rentals on each island visited.

One will suffice, since the new ferry will carry cars too.

A $90 million catamaran, similar to a craft that started service out of Mobile, Ala. last month, can carry 866 passengers plus a variable number of vehicles (depending on car and truck size).

According to the operating Hawaii Superferry, the vessel will have an average speed of 40 miles per hour and estimated crossing time of three hours on both its routes: Honolulu to Kauai and Honolulu to Maui. Although flight time is only 35 minutes, cars can't accompany passengers.

Ferry fares will be competitive with air fares but will vary by vehicle, as well as purchase time. A passenger who books early and travels without a car, for example, will pay only $42 each way but adding a vehicle could cost $55 (car), $65 (SUV), or $90-$100 (pickup, van, or truck).

Airfares for the same routes range from $39-$89 per person.

Funding for the ferry service came from both national and state sources. The company used $200 in federal maritime loan guarantees ro build its ships and was the beneficiary of a $40 million pledge from the State of Hawaii to make improvements in harbor facilities that would accommodate the 349-foot ferries.

As with any new venture, however, not everyone is wild about the idea.

Although Hawaii has not had viable ferry service in more than 25 years, opponents cite environmental concerns among a myriad of potential problems.

Several different groups are worried that ferry service will disturb migrating humpback whales, facilitate the spread of the "singing" coqui tree frog, or elevate pollution of the water (oil spills) and air (idling cars checking in at ferry slips).

Backed by Maui Tomorrow and the Kahului Harbor Coalition, the government of Maui County is making more waves now than the choppy waters between the Hawaiian islands may make for ferry passengers later. It has sued the state in the hope of forcing the ferry company to finance an environmental impact study -- something both the firm and the state say is not required.

John Garibaldi, chief executive officer of Hawaii Superferry, said his company has its own environmental controls, including route changes during whale mating season and thorough inspection of vehicles before they are allowed on board his ferries.

In an effort to keep the July 1 start date alive, the state is trying to settle the Maui suit.