Welcome to 'Rio Manhattan,' Washington Heights' most popular unofficial water park

New York City has three main rivers: the East, the Harlem and the Hudson. This summer, another mighty “river” was born — not around Manhattan but on the island itself.

Enter “Rio Manhattan” in Washington Heights, the brainchild of 45-year-old Alex Rolon. On hot days over the past two months, he’s been opening a fire hydrant next to a bike lane at 188th Street and Laurel Hill Terrace, putting a traffic barrel over the resulting stream and flooding the roadside to make a kind of lazy-river-meets-splash-park for residents.

The installation has attracted dozens of people from all over the neighborhood and beyond, giving kids a place to cool down and play next to Highbridge Park. It’s also gone viral on social media, making Rolon a city summer influencer whose videos have racked up tens of millions of views.

“ It was organic. Everything just fell into place,” he said last Friday as water gushed out of the hydrant and became a sparkling current on the sloping bike lane. “People love it because it's community-made. Everybody here played a part in this.”

In late June, Rolon said, he found a dead horseshoe crab at Orchard Beach and decided to pretend to catch it on camera as it floated down the makeshift river.

“We’re fishing here in Rio de Manhattan!” he exclaims in Spanish in an Instagram video where he bends down to pick up the crab while decked out in Knicks gear and a giant gold neck chain. “Ay, ay, ay!” he says, holding it up in the air.

The clip now has more than 19 million views, just a fraction of the engagement he’s built since.

Given the positive response to that initial video, Rolon said he began opening up the hydrant again. Soon enough, young people were showing up with bathing suits and pool floats to take advantage of the impromptu river — splashing around, shooting water guns and seeing how far they could drift down the street. It became a community ritual in sweltering weather. A local shop owner donated floaties for the cause, Rolon said.

Opening fire hydrants in the summer has a long history in New York City, dating back more than 100 years as a way to beat the heat. But few hydrant setups appear to have gone as viral as Rio Manhattan, which Rolon said has welcomed visitors from as far as Florida in recent weeks.

Last Friday afternoon, he showed up with a pair of pliers to muscle open the hydrant. As the water started flowing, he threw an orange traffic barrel over the torrent, pushing it into a high arc. The water park was open, and the corner came to life.

Rolon’s 10-year-old son Evan and a friend arrived to inflate inner tubes and a massive floating swan. A little girl confidently waded into the inundated bike lane, doing cartwheels in the water as her mother watched from a nearby park bench. Locals pulled up to wash their cars in the spray, and an ice cream truck materialized. Someone turned on bachata music.

According to city agencies, it’s illegal to open street hydrants for recreation without a special spray cap, which slows the flow of water and keeps the pressure up for firefighting purposes. Rolon said he has several such caps, and if firefighters drive by and see the stream is too strong, they’ll step in and bring it down. But he said city workers have never shut down the operation.

“We're just having fun,” he added. “We're not hanging out late and stuff like that, we're just doing it for the kids. And when we leave, we pack up everything.”

Rolon said the NYPD is supportive of his DIY water park “because it's a community thing and they see that everybody's together.”

“My biggest fear was, God forbid one of the children step outside or get hit by a car. So they said not to worry. The next day they came and they brought barricades to cover the whole area, so the cars knew to keep back, there’s children at play.”

Neither the NYPD nor FDNY responded to requests for comment about the setup's legality. The city Department of Transportation referred to the NYPD when asked about the obstruction of the bike lane.

The outdoor Highbridge Pool is only 15 blocks south of Rio Manhattan, but Michael, a 10-year-old visiting Rolon’s water park last Friday, said he prefers the street splash pad.

“Public pools are sometimes dirty in there, so this is why I just come to 188th [Street] to have fun,” he said.

Rolon said after the summer ends, he’s going to figure out other ways to bring the neighborhood together.

“I even have ideas for the winter,“ he said. “I might turn it into a little skating rink and just ski all the way down the bike lane. Ski Manhattan!”