A 21-year-old Melbourne man who died at a popular waterfall in far north Queensland was trying to save his father from the treacherous waters when the pair drowned, devastated friends have revealed.

Sisira Gajanayaka, 59, first got into trouble while swimming at Crystal Cascades, west of Cairns, on Tuesday afternoon.The veteran bus driver was travelling with a group of 18 people from four different families when tragedy struck. His 21-year-old son, Themi was trying to help save his father’s life when the pair drowned.The men were said to have been “struggling to get out of the water”, a police spokeswoman told 7NEWS.com.au.

Bystanders called emergency services about 5pm and a rescue operation was launched, but the men could not be found.Swift water rescue crews and two pump trucks were involved in the operation, before the men were found and pulled unresponsive from the water.Police said the pair were unable to be revived by paramedics and they were declared dead a “short time later”.More than 100 friends and family gathered to remember the pair on Wednesday, with loved ones telling 7NEWS Gajanayaka was a lovely friend who would do anything to help anyone.

“I couldn’t breathe when I heard the news,” family friend Marie Fernando said.“Everybody has lost a very good friend, that’s all I can say. We’re not going to get him back again.”Marven Jayawardena said Themi would be remembered as “someone unique and unapologetically him”.

“He would never fail to make us laugh or bring up our spirits in any moment,” he said.“We’ll miss him deeply.”The 21-year-old was said to be a talented musician and an avid Collingwood fan.