KEY LARGO, Fla. (AP) — Authorities say a 55-year-old French tourist died while snorkeling in the Florida Keys.

Monroe County Sheriff's spokeswoman Becky Herrin says Catherin Gray Molay of Paris was with her tour group at Grecian Rocks off the Key Largo coast on Tuesday afternoon when she surfaced without a mask.

She said the dive boat's captain told Sheriff's Deputy Benjamin Elmore that Molay was short of breath. The crew gave her oxygen but she became unresponsive and they started CPR. She was taken to Mariner's Hospital, where she was declared dead.

An autopsy will be performed to determine the cause of death.