A 51-year-old Lanai free diver who died Sunday morning after he was struck by a Lahaina-based tour boat was identified as Alan Amoncio, 51, a custodian at Lanai High and Elementary School.

Lanai police, the state Department of Land and Natural Resources and the Coast Guard are investigating the accident, which was reported at 10:30 a.m. in Kaumalapau Harbor.

Lanai Police Lt. Ricky Uedoi said Amoncio was diving with his wife and had set out flags to mark his dive position, and that a dive flag was attached to him.

A Maui County spokesman said 25 people were on a snorkeling outing on Zodiac tour boat, the Wiki Wahine, operated by Ultimate Whale Watch. Following the accident the boat operator dropped off the passengers and returned to the scene to help.

The harbor is on the west side of the island, about 7 miles from Lanai City. It is the main harbor for the island and where most fishing boats depart.