Lewis Pugh, a British endurance swimmer who is swimming the entire 315-miles of the Hudson River from the Adirondacks to New York City to highlight the critical role rivers play in a habitable planet, swims a section of the river, Wednesday, Aug. 30, in Castleton. (AP photo — Hans Pennink)

NEW YORK — The Hudson River snakes through forests and rushes over boulders in the Adirondack Mountains before settling into a wide, slow flow closer to New York City. It stretches 315 miles from source to end.

Lewis Pugh finished swimming all of it on Wednesday morning.

The 53-year-old endurance swimmer emerged from the water off the lower tip of Manhattan after a month-long journey, clad in a Speedo, cap and goggles. He smiled and raised his fist in triumph as he climbed out. Supporters who had gathered despite light rain at Battery Park cheered.

“It’s incredibly tough to swim for 30 days,” Pugh told reporters at a news conference. “And yes, it does take an enormous toll on you. But I can honestly say I feel rejuvenated.”

Pugh has powered through fatigue and sore shoulders for weeks. He has dodged tugboats and bobbing plastic garbage. And he insisted that any discomfort was worth it to highlight the Hudson and the importance of clean rivers.

“Seeing the Statue of Liberty on the horizon and seeing that beautiful torch, it just made me think that every single thing which we hold dear to us depends on us being able to drink clean water and breathe fresh air and take care of our planet so that is habitable,” he said. “Rivers are the arteries of our planet.”

The Plymouth, England resident has taken other high-profile swims, including one 76 miles long across the Red Sea and a 328-mile swim the length of the English Channel.

Swimming the length of Hudson has been done before, by Christopher Swain in 2004. While Swain wore a wetsuit, Pugh swam in a Speedo, generally trying to cover 10 miles a day.

For a recent leg south of Albany recently, he snapped his cap and goggles over his head before jumping feet first from the inflatable boat accompanying him. He made sure to first take a swig from a bottle of Pepto-Bismol, a nod to the less-than-pristine water. He also rinsed with an antiseptic mouthwash, washed up with surgical soap and wore ear plugs.

Support team members followed in the boat and a kayak.

The latter half of Pugh’s swim was on the Hudson estuary, the section of river affected by the tides that stretches from New York Harbor to above Albany. He tried to swim with the tide, but he said wind and choppy water could make progress more difficult.

“Imagine driving down a dirt road which has been corrugated, and that that’s the feeling when you’re swimming into this chop for hour after hour after hour,” he said before swimming a recent leg.

The challenges were different when Pugh started on Aug. 13 at Lake Tear of the Clouds, high on Mount Marcy. In the Adirondacks, parts of the river are too shallow to swim, so Pugh ran along the banks. Other fast-flowing stretches have enough rocks to create what Pugh calls a “high consequence environment.”

“I’m just in a Speedo, cap and goggles,” he said. “And so if you hit a rock, you’re really going to come off second best.”

Pugh had to take terrestrial detours around waterfalls, dams and locks, although he was able to swim through one lock. Those obstacles disappeared on the estuary, which becomes wider with more development crowding the shores.

The Hudson was notorious decades ago for being tainted by everything from industrial chemicals to old tires and sewer runoff. Even as late as 2004, when Swain swam the length of the river to encourage its continued cleanup, a New York Post headline read: Love That Dirty Water; Eco-Nut Swims The Slimy Hudson River.

Cleanups and tighter regulations have helped slowly transform the river into a summer playground for more kayaks, sailboats and even swimmers. The water is still not perfect. Sewage overflows into parts of the Hudson after heavy rains, for instance.

Still, Pugh said Wednesday that the Hudson River is still a powerful example of how a waterway can rebound.

“We must also never forget the history of the Hudson, because we came with saws and we hacked down the forests and we built factories and we poured industrial waste into the river … this river became a dumping ground,” Pugh said. “But then in the 1970s, New Yorkers said, ‘Enough is enough.'”