New York City Mayor Zohran Mamdani revived a long-dormant City Hall tradition on Saturday by donning a full suit and tie and diving into a public pool in East Harlem to mark the opening of the city’s 2026 outdoor pool season.Mamdani’s suit-clad dive marked the beginning of New York City’s summer pool season, violating the pool’s dress code.The mayor jumped into the Thomas Jefferson Pool on East 114th Street along with Manhattan Borough President Brad Hoylman-Siegal and Parks Commissioner Tricia Shimamura, becoming the first New York City mayor to participate in a ceremonial plunge in more than a decade. The New York Post noted that Mamdani technically violated pool rules by entering the water in formal attire. Mayer later reposted the tabloid’s story on X along with a video of his dive, joking: “When they said ‘wear a suit,’ I agreed…”The annual tradition was abandoned during the tenures of Eric Adams and Bill de Blasio. Michael Bloomberg was the last mayor to hold the office in 2013. Mamdani indicated in March that he might be “committed” to reviving the ritual when asked about it by City reporter Katie Honan.After emerging from the waist-deep water, Mamdani greeted residents gathered at the pool and marked another milestone for the city. “We are very excited to celebrate 90 years of public swimming in our city,” Mamdani told reporters in his soaked suit. “This is a moment that New Yorkers are celebrating across the five boroughs.”The anniversary dates back to 1936, when then-Mayor Fiorello LaGuardia, whom Mamdani has often described as New York City’s greatest leader, oversaw a major expansion of the city’s public swimming facilities. Supported by then-President Franklin D. Roosevelt’s Works Progress Administration, the project opened 11 new public pools across the city. Known for its distinctive architecture and advanced chlorination and filtration systems, the pools were regarded as landmark public works and continue to serve New Yorkers nearly nine decades later.