Dominican media reports and friends identified the two men as Joe Valentino, 64, and Nick Carlucci, 63.
They were staying at a hotel in Cabarete, a town in the country's Puerto Plata province known for its tourism and beaches.
Carlucci was swimming in the ocean on Tuesday afternoon when he "got into some difficulty," according to Valentino's longtime friend Antonio Sciascia.
"He was yelling and calling for help," Sciascia, who was told about the incident by close family friends, said in an interview Saturday.
Valentino went into the water to help him, and "a big wave came in and pulled them away," he said.
Their bodies washed up on the beach soon after, he said.
A medical examiner determined drowning was the cause of death and their bodies were sent to a coroner in Santo Domingo, according to the local media outlet El Nacional.
"It's a big loss for the community," said Sciascia, a Montreal lawyer and president of Quebec's chapter of the National Congress of Italian-Canadians.
Sciascia said Valentino "always had a big smile on his face."
Valentino's daughter, Rosanna, told Radio-Canada Saturday the bodies would be returned to Canada within days.
She said the family doesn't have many details about what happened, but was told a woman saw the two men swimming in the ocean and called for help.
The woman didn't help them herself because she was afraid she too might drown.
Rosanna Valentino said it appears that the two men were swimming in a dangerous area.
Canada's Department of Foreign Affairs confirmed the deaths.