It was a last-minute decision to hike to Moon River Falls.

The eight campers wanted to catch a final swim Sunday before they headed home to Barrie. As they dried off, they watched a group of men jump off the rocks into the furiously swirling waters below.

“I remember thinking, ‘What are they doing? That’s so dangerous,’” said Ryan Airlie, 19. “We were warned not to go in because the current was so strong.”

Then they heard screams. Seven men were caught in the harsh current.

A man ran over to the young campers, ages 17 to 24, pleading for towels. The group grabbed what it had and yanked off shirts, knotting them to make a makeshift rope.

By this time, three of the swimmers had already disappeared. Police recovered two of their bodies yesterday.

“We were just acting on instinct. We knew we had to move fast,” said Derek Airlie, 24.

The brothers, alongside friend Jamie Palomaki and a man there with his family, climbed onto a rocky outcrop and hauled out one of the swimmers.

Three other swimmers continued to be tossed around in the vicious whirlpool.

“The guys kept spinning in a circle. It seemed to keep pulling them under,” said Michael Curatolo, 18. “We yelled: ‘Hold on! Keep swimming!’”

The men managed to lasso two swimmers and pull them to a rock ledge. But the towels were soaked and heavy; they needed something lighter to reach the final swimmer.

Using a machete, rescuers chopped down a sapling, tied the tree to the towels and reeled in the last swimmer.