A 17-year-old boy who died after being hit by a fishing boat while free diving in Maunalua Bay on Sunday was identified by the medical examiner yesterday as Keahihoku Lum, a senior at Farrington High School.

Police, the state Department of Land and Natural Resources and the Coast Guard are investigating the incident.

Police said the incident happened at 12:57 p.m. The teen was diving with friends when he was run over by a fishing boat, they said.

The boat operator stopped to render aid and brought the diver to shore, police said.

It's not clear whether the diver was near a boat channel or the boat was outside the channel.

Deane Gonzalez, a Hawai'i Kai resident who has dived in Maunalua Bay for more than 45 years, said it is not uncommon to find divers in or near the boat channel. He estimated that he sees divers in or very near the channel about every fourth time he heads out to sea aboard his Boston Whaler from the Hawai'i Kai boat launch ramps.

In the channel itself, or in the bay in general, it is imperative for boat operators to keep a keen lookout for anything in the water, he said.

"Whether it's palm fronds, turtles, kayakers, windsurfers of whatever, it's up to the boat operator to avoid a collision," Gonzalez said.

Divers are required under state law to use a dive flag when diving or swimming underwater in navigable waters that are under state jurisdiction. Divers are also required to surface within 100 feet of their flags while in open waters and within 50 feet of their flags in navigable streams.

A dive flag is a red flag, measuring not less than one square foot, with a white diagonal stripe running from the upper left hand corner to the lower right hand corner (from masthead to lower outside corner).

The flag may be attached to a float or mounted on the highest point of a vessel being used as a platform up to 16 feet in length and visible from all directions. Vessels over 16 feet must display a 20-by-24-inch dive flag along with a blue alpha flag mounted at the highest point of the vessel and visible from all directions.

An alpha flag is a blue flag with a white horizontal strip running from the upper left side to the lower left side. It is the international signal for a diver down.

All vessels, including personal watercraft, are prohibited from approaching within 100 feet of a displayed diver's flag in open waters and 50 feet in a navigable stream unless conducting scuba, snorkeling, or free diving activities. These vessels may approach within the restricted area of a dive flag at a speed slow enough to cause no wake.

Failure to employ a dive flag and violating the no-approach/slow-no-wake zone around a dive flag is punishable by up to six months in prison and/or a fine of up to $1,000.