It’s about tide!

After a two-year hiatus, New York City’s only swim-bike-run race — now known as the Big Apple Triathlon — returns Saturday, with roughly 1,300 endurance athletes expected to dive in, quite literally, to the Hudson River.

If conditions cooperate, competitors in the longest-distance event will swim nearly a mile along the shoreline before cycling 25 miles on the West Side Highway and running 6.2 miles through and around Central Park.

The event, previously called the New York City Triathlon, dates back to 2001. Its recent track record, however, has been turbulent, marked by scheduling complications, extreme weather and repeated changes to the course.

“I believe every edition since 2017, we either had to shorten the run, shorten the bike or cancel the swim,” former race director Alex De Gracia of Life Time told the Post. His organization sold the race in 2023.

The 2019 race, then held in the summer, was canceled because of dangerous heat. In 2021 and 2023, concerns over water quality forced organizers to eliminate the swim and replace the event with a run-bike-run format. In 2022, temperatures forecast to reach the 90s prompted officials to cut the bike and run courses by at least half.

Organizers canceled the 2024 event before registration even opened. They had hoped to avoid the worst summer heat by shifting the race to the fall, but could not agree with the city on a workable date. Many local triathletes moved on.

Now, with a new organizer, Alpha Win, and an early-fall date, the starting gun is set to sound once again. About half the field is traveling from outside New York City, and most participants paid between $350 and $625 to compete. They are hoping this comeback finally sticks.

“I was super excited when I heard about it; I loved the New York City Triathlon,” said Matt Stern, a 32-year-old Manhattan attorney who competed in 2023 and describes the course as “epic.” “I think it’s amazing to be able to swim, bike and run in the city. You train here every day, so to actually be able to race here is awesome.”

Why tri? 

A triathlon combines swimming, cycling and running, typically in that order so athletes enter the water before exertion sets in. The shortest format, known as a sprint, usually covers about 16 miles. The most famous long-distance race, the Ironman, spans 140.6 miles and includes a full marathon.

New York City’s event has traditionally been an “Olympic” triathlon, essentially twice the distance of a sprint. This year, however, Alpha Win is offering “a distance for everyone,” its motto, with a sprint, relay, aquabike — swim and bike — and duathlon, which features a run, bike and run.

“People associate the name ‘triathlon’ with Ironman, and they think, ‘Oh, that’s some crazy goal,’” Stern said. “But I think triathlon is really accessible for a lot of people.” He was drawn to the sport three years ago when he joined his cousin for a sprint triathlon in Montauk. At the time, he could barely swim. Today, he is an Ironman finisher and a member of Empire Tri Club.

“It’s fun to be able to push yourself, see what you can do, how far you can take yourself, how fast you can go,” Stern said. “And the community around you is what makes it really special.”

The sport draws “not just your elite, very, very fit-looking people; it’s certainly a diversified group,” said Tommy Struzzieri, Alpha Win’s CEO and race director. The Saugerties, New York-based company has staged more than 200 races since 2010. “That’s why I love standing at the finish line,” he added.

Getting athletes to that finish line in New York City, though, requires plenty to go right.

Weather is the first challenge. “Racing in the northeast has a very limited window,” said Joel Volterra, a TriLife NYC triathlon coach and one of this year’s competitors. Spring water temperatures can be dangerously cold, summer heat can make the air unsafe and fall brings the unlikely but genuine possibility of hurricanes.

Then there is the city’s packed calendar. Organizers must find a weekend day during that narrow window that is not already consumed by a protest, parade, presidential visit or playoff game.

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Unlike races in many other places, where closing roads for cyclists does not require diverting traffic from a major Manhattan artery in the city’s most populous ZIP code, a New York multisport event involves far more than course design. Protecting the swim can also mean coordinating with the Coast Guard, while the entire operation requires approval from city, state and federal agencies.

“You’ve got DOT, you’ve got Parks, you’ve got police, you’ve got emergency services … you’ve got Riverside Park and Central Park, you’ve got all the community boards that are affected,” Volterra said. “So it’s any one of those things or a bad weather event [that] can derail it.”

There’s something in the water — or is there? 

And then, of course, there is the Hudson. But before anyone talks trash, let’s talk tides.

“When people think of a river, they think of a river moving in one direction. That’s not what happens in the Hudson,” said Deanne Draeger, founder of Urban Swim, which hosts open-water swims around the city and advocates for more accessible waterways. 

Rather, what happens in the Hudson — technically a “tidal estuary” — is a series of “tide cycles,” Draeger added. “It’s constantly flowing north and south, and north and south again. So that’s one of the most important things planners have to take into account.” 

As such, this year’s swim route heads north to help participants go with the literal flow. Man-made barges mark the leg’s start and end. 

A “safety flotilla” including 60 lifeguards on paddle boards, FDNY and NYPD boats and other vessels staffed with paramedics and rescue divers will shield the lane from marine traffic and save, if necessary, swimmers in distress.

The Big Apple Tri is “one of the fastest swims [in the sport], but that doesn’t mean we think every athlete is going to be 100% comfortable jumping in the Hudson,” Struzzieri said. “So we have to be prepared for all parts of that process.” 

Indeed, a self-proclaimed beginner triathlete sought comfort from Reddit after signing up for this year’s challenge: “I’m training well for the swim and I’ve done a bit of open water practice but I am not sure that I am really mentally committed to swimming in the Hudson.” 

But despite its radioactive reputation, the river often tests safe enough for swimming, Draeger said. Decades of wastewater improvements and federal regulations have drastically reduced pollution and cut “fecal coliform bacteria” in the New York Harbor by 95% since 1970, one 2007 report showed. 

Since then, investments in the city’s sewage system, as well as efforts from nonprofits like the Billion Oyster Project, have revitalized water quality and ecology further. Without these upgrades, plus careful monitoring, Draeger’s group wouldn’t be able to safely guide about 200 swimmers in open-water events around the local waterways each year. 

“The river isn’t just a pretty view; it’s public space. This is part of the city, which is one of the things that I think is fantastic about the New York City Tri,” said Draeger, who completed it in the past. “It’s an opportunity when people can get in the water, and you have an experience of New York City that’s completely different from anything that you’ve had before.” 

That said, the Hudson is hardly a glacial spring. No one should be diving in outside of an organized event. And, in the wrong conditions, even such contests can present risk. Due to the city’s antiquated sewage system, experts say, heavy rainfall is enemy No. 1. 

“After a big storm, all of the contamination that’s on the city streets from the pets, from the animals, from trash, gets flushed into the catch basins and over land into the water and goes through these outflows that the city is desperately trying to address,” said Volterra, a civil engineer by day. 

But this year — gangrene-free fingers crossed — participants appear to be in the clear. The Department of Environmental Protection has been testing the river for months. Alpha Win has been consulting with an on-site meteorologist for weeks. The sky has stayed dry for days. 

“So far,” Struzzieri said Monday, “so good.” 

For a race that has spent years battling the elements, that’s a promising forecast.