An autopsy will be held for a 69-year-old California woman who lost consciousness this morning on a snorkeling trip to Molokini islet, Maui police said.

Efforts to revive the woman on her tour boat and by Coast Guard crews were unsuccessful. Police said officers responded to the Kihei Boat Harbor shortly after 9 a.m., but the woman was unresponsive.

The identity of woman, from La Mesa near San Diego, will be withheld for 24 hours to allow her family to notify extended family and friends, police said.

The preliminary investigation revealed no signs of foul play, and an autopsy will be scheduled, according to police.