Bonačić was born in
Split to a
Croatian father and
Slovenian mother. He had an elder brother Vojko and a sister Nevenka. He graduated in natural sciences in
Zagreb, and took up rowing to build muscles, as he weighed only 56 kg with a height of 183 cm at the time. After retiring from competitions he worked as a professor of
geography,
meteorology and
oceanography at maritime schools and also served as a coach and referee in rowing and sailing.[2]
After the death of
Željko Čajkovski on 11 November 2016, he became the oldest Croatian Olympic medal winner.[3] Bonačić died on January 24, 2020, at the age of 90 following a short illness.[4]