A search team found the five at Lipur Sungai Bantang Forest at 10.50am Thursday. Police received a distress call from the group at 3pm on Wednesday.
Segamat OCPD Supt Abd Majid Mohd Ali said Australian Chris Birchill, in his 40's, could have died of a heart attack.
Birchill's body had been sent to the Segamat Hospital for post-mortem.
“The remaining survivors, from South Africa and United Kingdom, are now being treated at the hospital," said Supt Abd Majid.
The forest is a popular tourist destination located in the Labis Forest Reserve, about 8km from Bekok town.