An activist-swimmer renowned for braving the Gowanus Canal just completed another sludgy stunt.

Despite illness, intense back pain and even a blizzard, Christopher Swain, 49, reached his latest destination Thursday: The Verrazano Bridge. Swain swam a total of 27 days to complete the 133-mile swim from Montauk to the Verrazano. He traversed the entire length of the Long Island Sound, East River and the rough waters of the Hell Gate to raise awareness for the region’s polluted waterways.

“I want all those water ways — Long Island Sound, East River, New York Harbor — to be clean. I want them to be safe for swimming every day,” said Swain, still in his wet suit, in Brooklyn Bridge Park. “By putting my body in here with the sewage, floating trash and jellyfish…the reason I went through all of that is because if you want something to change you have to do whatever it takes.”

Swain gave credit to the city, state and federal governments for progress made in the last few decades; but he wants agencies to do more to separate sewage from rainwater, and avoid routing waste runoff into the NYC’s bodies of waters during a storm.

“Twenty-odd years ago it was a joke when Kramer does it on Seinfeld. Now if it hasn’t rained in a couple of days, it’s possible,” said Swain, a Manhattan native. “If the city, the state and the EPA were willing to work together and incentivize separating storm water from sewage it would go a tremendous distance towards making these waterways swimmable every day.”

Swain is no stranger to navigating the trash infested waters of New York Harbor. In addition to swimming the Gowanus, he has stroked through the Hudson River and Newtown Creek. Both pale, however, in comparison with his swim through the Columbia River in the Pacific Northwest — his favorite thanks to the mineral water springs that feed into it. “I could drink the water I was swimming in,” he said

“I dream of a day when people could come on a 95-degree day and swim at a Pier 4 beach after work,” Swain said.

Ed Timbers, a spokesman for the city’s Department of Environmental Protection, responded to Swain’s calls by pointing to the city’s green infrastructure and clean-up commitments that have led to the return of unusual wildlife in New York Harbor, such as humpback whales.

“New York City has invested more than $10 billion to clean up local waterways and testing shows that our harbor is cleaner today than it has been in more than a century,” Timbers said in a statement.