The trio, a man and two women, were found outside of Dalat, a mountainous city that draws tourists with its crystal lakes and steep waterfalls.
It was not immediately clear how they died.
"We are working on the reasons for their deaths," Dalat city's deputy police chief Bui Duc Ro told AFP.
State-run media said the two women were aged 25 and 19 and had entered Vietnam at the start of the month, but the police officer could not confirm their identities.
Emergency workers reportedly climbed down a steep slope near the waterfall to recover the bodies, which were found wearing life jackets.
Visitors can rappel down the 20-metre waterfall as well as luge around the site.
In 2013 British scientist Jamie Taggart went missing in Vietnam's Sa Pa jungle and was never found despite search efforts by local authorities.
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