New York (CNN)It usually takes a lot to get a rise out of New Yorkers.
But for Dion Cini, a middle-aged former Marine from the Upper West Side, it actually requires very little.
Nearly every day, Cini climbs into an 18-foot scull rowing boat and paddles the Hudson River along the Manhattan shoreline. Before shoving off, Cini hoists a prominent flag that reads "Trump 2020."
And then he waits for the reactions to pour in.
"Sometimes you hear 'I hope you get hit by a boat! I hope you drown!" he said. "From the top of their lungs as loud as they can. I get it all the time."
It's a simple act of defiance for a supporter of President Donald Trump who lives on an island that voted overwhelmingly for Hillary Clinton. In 2016, nearly 87% of Manhattan voters supported Clinton, second only to neighboring Bronx County, where Clinton support crept closer to 90%. (Cini makes a point to row around both.)
"There's so much fear of Trump in New York," Cini said.
He started hoisting the flag from this boat this spring after seeing a swell of protests against Trump in the city. He previously enjoyed walking the flag through the streets of Manhattan, which attracted throngs of angry people who told him to leave.
Why does he do it?
"Because I can," he said.
On a recent afternoon, Cini, wearing a mesh shirt and no life jacket, pushed off into the river and began paddling through choppy water toward lower Manhattan. In his months of rowing with the Trump flag, he finds that support for his effort increases as he rows south, home to the city's financial district and areas teeming with tourists who live elsewhere.
Cini rowed close to shore, giving thumbs up to people standing on the docks and walking paths that line the river. Some reciprocated, others gave a thumbs down, and plenty extended a different finger.
"Donald Trump is a piece of sh**!" a young man shouted from shore.
"F*** Trump!" another man hollered from a dock near a riverside restaurant.
Cini doesn't ignore their taunts—he provokes them further. He engages and argues back.
As he paddled toward Battery Park, with the Statue of Liberty behind him, crowds grew friendlier. A ship of tourists cheered him on, and the "thumbs up" signs came more frequently.
Cini has no plans to stop. The responses, he says, drive him.
"I'm out of goals," he says. "I have nowhere else to go in the world. I don't really want to climb Mt. Everest. I almost see this as climbing Mt. Everest. It's one of the biggest challenges I've ever done in my life -- knowing how many people do not like me in a small space and continue to survive."