The Big Apple’s public-pool season is already more sink than swim.

Mayor Eric Adams declared Thursday that 50 public swimming pools are open for the summer, although city officials later clarified the sites will continue to face partial closures because of an ongoing lifeguard shortage — and there was a temporary shutdown hours later at the very pool where Hizzoner made his splashy announcement.

Whole sections of the newly renovated Astoria Pool were closed just hours after Adams left it, leaving a long line of people waiting outside.

A security guard told The Post that the hopeful pool-goers, who snaked around the block, wouldn’t make it inside before the pool closed at 7 p.m.

“I didn’t realize it was closed,” said Julia Macneva, 38, an Astoria artist, filmmaker and writer who showed up at entrance Thursday hoping to swim in the laps section.

As for others arriving later in the day, “It doesn’t matter if they come at 11 a.m. or at close — you’re just in the line doing nothing but wait,” she said.

Closures at the city’s public pools have thrown a wet blanket over many New Yorkers’ plans in recent summers, in large part because of a lifeguard shortage. Since 2022, the city has been able to recruit far fewer than the roughly 1,000 lifeguards needed, officials have said.

The city’s efforts to hire enough lifeguards for this season belly-flopped, too, with officials Thursday quietly admitting public New York City pools will suffer rolling partial closures yet again thanks to fewer staffers.

“As with last year, most pools will have partial closures based on the staff we have available,” a parks rep told The Post.

“We will continue to get more lifeguards through July, so we will be able to open more sections as the summer progresses.”

Adams presented a sunnier view as he crowed about the city reopening dormant pools this year after renovations.

He said the city has already employed more than 600 lifeguards, with Parks confirming more were being hired before July 4.

“We’re opening our pools today with more guards than we had this time last year,” Adams said.

Three of the city’s 53 outdoor pools remain shut, but only for construction, Big Apple officials said. 

The closed sites are at the Tony Dapolito Recreation Center in Hudson Yard, the Tompkins Square mini pool in East Village and a new pool in Harlem. 

During Adams’ 2021 mayoral campaign, he promised at least 1% of the city’s budget would go to the Parks Department, but since then, hiring freezes and cuts have plagued the agency.

When asked about the cuts and potential for a reversal, Adams stressed that he’d like to “let the process play out with our leaders.

“And I say this over and over again, we’re going to land the plane,” he said about the upcoming budget.

An Astoria pool-goer who only gave his first name, Michael, agreed the city needs a proper budget.

“The city takes billions of dollars and spends it on high-tech weaponry, riot gear, stuff like that, while we have to wait out here [on line],” he said. “That’s insane.”