KEY WEST, FL (AP) -- A man aboard an NOAA vessel died while diving near Key West and authorities are currently investigating the reasons. The 54-year-old from Ramrod Key was not identified pending notification of his family.

According to the Monroe County Sheriff's Office, the diver and his buddy were surveying the sea floor on Monday for an upcoming coral restoration project. They were heading back to the surface -- from 80 to 100 feet under -- and reached a decompression stop, at which point the buddy noticed the man sinking downward.

Authorities say other divers on the National Oceanic and Atmospheric Administration vessel went into the water and retrieved the man. They performed CPR and called the Coast Guard. A helicopter took the man to Lower Keys Hospital, where he was pronounced dead.

An autopsy has been scheduled.