WAILUKU, Maui — A tourist killed Saturday when his rental convertible plunged 140 feet into the ocean near Honolua Bay was driving on a section of road that visitors are discouraged from using due to hazards that include rockfalls and steep drop-offs without guard rails.

Police said Kevin P. Curran, 42, of Ozark, Mo., was headed toward Lahaina in a 2006 Ford Mustang when he apparently failed to negotiate a left curve at milepost 34 and plummeted into the sea at an area known as Windmills, or Punalau Beach. It is not known when the accident happened, although a passer-by who noticed the car in the water called 911 shortly after noon.

Curran, who was honeymooning on Maui, was alone and not wearing a seat belt, police said. He died from "multiple traumatic injuries" primarily to his neck and chest, "but we can't exclude the possibility that drowning played a role," said Maui pathologist Dr. Anthony Manoukian, who performed the autopsy.

Curran was ejected from the convertible as it spiraled to the left during its descent, and he apparently was injured when his body hit the vehicle in the water, Manoukian said. It's uncertain whether seat belts would have saved him, he said.

Curran's body drifted to the shoreline, where it was found.

Most car-rental companies on Maui advise customers that their contracts restrict them from traveling on Honoapi'ilani Highway past Honolua Bay. The two-lane highway, which continues on through Kahakuloa Village and into Wailuku as Kahekili Highway, was carved into Maui's remote, rugged northern coastline and narrows to a single lane in some sections. Some portions of the highway are little more than dirt and gravel, and landslides and falling rocks are not uncommon.

Pi'ilani Highway between Kipahulu and Kaupo, on the back side of Haleakala, is another stretch where rental cars are discouraged for the same reasons.

An informal survey yesterday of Hertz, Budget and Dollar car- rental companies indicated that motorists are told to avoid the restricted roads, and if they ignore the warning, they are on their own as far as getting help for damage and breakdowns. It was not immediately known which company owned the car Curran was driving, or whether he was advised of restricted roads.

The victim and his bride, Jill Curran, arrived on Maui on May 13 after marrying May 5 in Eureka Springs, Ark.

The two had fallen in love during a trip to Hawai'i in 2003 and had decided to honeymoon here, said Jill Curran, 43.

"He's the best person in the whole world. He was my best friend," she said by phone from the Lahaina Shores Beach Resort in Maui. "I'm here by myself."

Jill Curran said she went to buy lunch Saturday while her husband explored the island by car. Soon after she returned, police arrived and told her that he had died in a car accident.

"I'm in shock," she said. "I don't understand what happened."

Kevin Curran worked as a lawyer for 17 years, helping abused children. He stopped practicing law in 2004 to start the company balance360.com, selling a training device he invented for surfers and people undergoing physical therapy.

Despite the warnings about Honoapi'ilani-Kahekili Highway, guide books, Web sites and other sources promote the coastal route's stunning landscapes that include jagged rock formations, the Nakalele Blowhole, and Pohaku Kani, or Bell Rock, which marks the site of a natural seaside pool that has seen several deaths in recent years after visitors were swept into the ocean by waves.

Luxury subdivisions, roadside stands and art galleries have sprouted along the highway as the tourist traffic increased.

Some tourists who stop at Ululani by the Bay in Kahakuloa say they are surprised and a little scared by the road, said snack stand owner Ululani Ho'opi'i.

"With so much traffic coming in and going out, we know the road well, but you still have to be aware of the cars that are coming and going," she said.

Her husband, Richard Ho'opi'i, said visitors also are unfamiliar with local road etiquette when confronted by oncoming cars on narrow roads.

"You can view all of Maui's scenery on the Internet, but if you do decide to drive, the best thing is to talk to people who have lived there all their lives," said Ho'opi'i, a retired county worker and noted entertainer.

He said he would like to see more caution signs, reflectors and guard rails on the highway, but acknowledged there isn't always room on the winding mountainside road for safety improvements.

Other cars have gone off the cliffs along Honoapi'ilani-Kahekili Highway, parts of which are owned by the county and others by the state.

On April 27, 2006, a 45-year-old man from Park Ridge, Ill., driving a rented 2005 Chrysler Sebring convertible, apparently missed a curve and dropped 300 feet onto the rocks below Kahekili Highway near Kahakuloa.

In another case, a 35-year-old Napili man and a 3-year-old boy were killed Nov. 18, 2001, when their sedan went off Kahekili Highway at Makamaka'ole Gulch and plunged to the rocks below.

State transportation spokesman Scott Ishikawa said officials will request police reports on the latest accident to review the need for any additional highway safety measures.

Reach Christie Wilson at cwilson@honoluluadvertiser.com.