A rare jet ski fatality prompts an investigation and raises questions about the state's regulation of commercial thrill craft operators.

Some of the thrill was gone for Marcy Taylor, as she watched her 21-year old son and 16-year-old daughter zip around Keehi Lagoon on jet skis Tuesday morning.

"I just found out about the accident after my kids were already out there, so I'm a little nervous," said Taylor.

Her family, visiting from California, was familiar with jet skiing and her kids wanted a little adventure while they were here. They went out to Keehi Lagoon, one of four designated areas where commercial jet ski operations are allowed.

In the lagoon, each company gets a separate small area for riders.

Jet skiers are required to stay in those designated spots, but race on watercraft built to top speeds of 50 mph. Those speeds are not restricted by the state.

"If they are in the designated areas, it is up to the commercial operator to decide the speed of the craft. We don't put a speed restriction in that zone," said Ed Underwood, the Boating Administrator for the Department of Land and Natural Resources.

That speed had Taylor watching with worry. "We're on vacation and we want to come back whole," said Taylor.

Over the weekend, 16-year-old Kristen Fonseca went out for a jet ski ride with a competitor, Aloha Jet Skis.  According to the state, the company has been operating at Keehi Lagoon for the past 12 years, without any accidents -- until Sunday.

"There was a collision involving two skis," said Randy Awo, with the department's enforcement division.

According to witnesses, a young man on a jet ski was passing another rider when he slammed into Fonseca from behind. The 16-year-old was taken to the hospital, where she died from injuries in the collision. The other rider suffered serious injuries.

Underwood said accidents are rare for commercial jet ski operations. He could not recall the last time there was a death on a personal watercraft in the islands.

"No, I can't. We have not had one, that I am aware of," said Underwood. He also stated that it is too early to tell if the fatal accident will lead to any changes to the state's regulations of commercial thrill craft businesses.