Melbourne-born Elly Rose Warren was on a diving trip in Mozambique when she was found dead near a marketplace this week.
Authorities have told Mr Warren she was found murdered in a toilet block near the market.
“They think that it was pretty bad, sexual assault,” Mr Warren told AAP on Thursday.
The grieving father is now trying to contemplate life without his “wonderful girl”.
“She was full of life,” he said, adding that she was a keen sailor and loved travelling.
Ms Warren was set to head to New Zealand before starting a degree in marine biology in Townsville.
In Mozambique, Ms Warren was undertaking a volunteer marine conservation dive program which was run by Underwater Africa.
A spokesman for the company said Ms Warren had finished the program with them and was continuing to travel by herself.
“We are absolutely shocked and devastated with what happened,” he said.
The Department of Foreign Affairs and Trade says it is “providing assistance to the family”.
Mr Warren hopes to find justice for his girl.
“I just hope they catch the bastards,” he said.
“They’ve got to do something.”
Elly’s sister Kristy Warren described on Facebook the moment her family learned of the death.
“My sister was in Africa whilst my mum got a phone call from one of the backpackers saying to her that her daughter has been murdered, as I heard that my heart dropped,” she wrote.
Mr Warren’s boyfriend, Luke Tempany, said she would be deeply missed by everyone but especially her little brother Sam.
“I want her to be remembered for her love of the oceans, whales, sharks and all living animals,” Mr Tempany told AAP in a statement.
“She had such a beautiful heart that wanted to travel the world diving all the waters, exploring caves and swimming with all different fish.”
DFAT’s Smartraveller website warns Australians visiting Mozambique to exercise a high degree of caution and reconsider their need to travel in some areas.