According to the Galveston County Sheriff's Office, the man went into the water around 1pm Sunday in the 2700 block of Beach in Gilchrist on the Bolivar Peninsula.
Officials said the friends with whom he was swimming went ashore and motioned for him to come out of the water, but he kept drifting farther away.
The man's friends were able to pull him to land, but he was unresponsive. He was transported to the University of Texas Medical Branch where he later died.
The victim, who was in his 60s, had previous medical conditions. It was unclear Sunday if he drowned or died because of another medical issue.
An autopsy will be conducted to determine his cause of death.