A police investigation into the tour company had since been opened, she said.
Maumere Search and Rescue office head Supriyabto Ridwan said Liu fainted after swimming and although CPR was performed, he was unable to be saved.
International Society of Political Psychology said Liu was “a loving father and husband and family man and he was a treasured friend and colleague to many”.
The society said it was “deeply saddened” by Liu’s death in an online tribute.
“James was a beloved member of our ISPP community, known for his warmth, intellect, and dedication.
“We are forever grateful for the profound contributions he made to the field of political psychology. Our hearts go out to his family, friends, and colleagues during this difficult time.
“He will be greatly missed by all who knew him.”
Liu was born in Taiwan but grew up in the United States with his family.
Liu worked at Victoria University from 1994 to 2015 where he was a professor of Psychology and co-director of the Centre for Applied Cross-Cultural Research.
Liu then worked as a professor in the School of Psychology at Massey University.
Jaime Lyth is a multimedia journalist for the New Zealand Herald, focusing on crime and breaking news.