A Toronto man drowned in the Ottawa River on Saturday evening in a tranquil bay as his friends looked on in horror.

Thang Duc Ngo, 28, was on a rafting trip near Foresters Falls, Ont., about 100 kilometres west of Ottawa, when the party pulled off to a popular swimming spot. Dubbed "Miami Beach," there's a sandy beach to lie on and a three-metre rock to jump from.

Wilderness Tours boss Joe Kowalski said Ngo had leapt from the rock, surfaced and began to swim back. Suddenly, Ngo sank beneath the water.

"This is all in calm water," Kowalski said.

Wilderness Tours staff swam to his aid, pulled him out of the water and tried to resuscitate him, but there was nothing they could do. His friends told the rafting company that Ngo was a capable swimmer.

They had returned to Toronto on Saturday night.