A pathologist at Cork University Hospital said Martin and Clarissa McCarthy both drowned, The Irish Times reported.
McCarthy's wife, Rebecca, said she returned to their farmhouse on the coast near Ballydehob from a visit to friends Tuesday evening and found her husband and daughter missing. She launched a search with neighbors and called police after a note from her husband was discovered.
McCarthy, 50, was much older than his wife, who first came to the area on a visit from California 15 years ago. A neighbor said they married in 2006.
John O'Brien, a neighbor, had known McCarthy since their schooldays.
"He was a mighty worker altogether. You would always see him coming and going over the road with the cattle," O'Brien told the Times. "I had not seen him in about a week though, which I thought was unusual."
Michael O'Regan, who commanded the officers who found Clarissa's body at about 1:30 a.m. Wednesday in a cove below the farm, said the discovery was one of the saddest in his 50 years with the Coast Guard. Rescuers tried to revive the little girl for an hour and a half.