The Monroe County Sheriff's Office said in a news release Sunday that the 70-year-old man was from Houston, but his name was not immediately released.
Investigators say the man and a female friend were on their second dive Saturday near a lighthouse off Key Largo. The friend told authorities the pair resurfaced after she noticed a leak in a piece of his equipment.
The man panicked and began swimming away from their boat. Investigators say the woman swam after him and found him unresponsive and not breathing.
They were taken aboard a nearby private boat and then assisted by the Coast Guard and state wildlife officers. The death is under investigation.
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