Officials say John O'Sullivan, 54, was pronounced dead at a hospital in the Caymans on Wednesday.
The La Porte native's family is having a tough time dealing with the tragedy. His daughter, Annette O'Sullivan, spoke out on behalf of the family Saturday.
"I mean he absolutely loved the water," she said.
Authorites said O'Sullivan was unconscious when he was taken aboard the vessel Cayman Sky near the Kittiwake dive site around 3pm Wednesday.
His family tells us he suffered a health complication during that trip.They say O'Sullivan passed away on the boat while heading back to shore.
Right now, no further details of his death are being released.
Many people may remember O'Sullivan as one of the lawyers for Andrea Yates -- the Houston-area mom who killed her five children back in 2001.
Family members tell us funeral arrangements are still pending.