Three Japanese tourists died while swimming or snorkeling this week on Oahu. All three were men in their 70s.  The Honolulu Medical Examiner's office says 76-year-old Fumio Kudo, from  Omori, Japan, got into trouble at Hanauma Bay at about 11 a.m yesterday.  He died at the hospital. An autopsy will be conducted Monday to determine cause of death. On Monday, 73-year-old Kazuo Takino of Osaka, Japan drowned just before 2 p.m. while snorkeling off Heeia Kea Pier. An autopsy determined it was accidental drowning.  On Wednesday, 79-year-old Fumio Ando of Aichi, Japan died while swimming at the Hilton Hawaiian Village Lagoon in Waikiki. He was taken in critical condition to the hospital, where he died. An autopsy determined he drowned.