Southampton Town Police tell Newsday (http://bit.ly/NU6EAG ) the revelry started Saturday on the sandbar in Shinnecock Inlet.
Police were called just after 8 p.m. and found onlookers pulling a 23-year-old out of the water.
He tried to flee when told he was being arrested on a charge of violating the town code by swimming in the channel.
He was found nearby, and police added a charge of obstructing governmental administration.
Another 23-year-old was pulled into the ocean by a current and rescued by the Coast Guard. The agency also rescued a 20-year-old from the inlet.
The three, plus 37 partygoers from the sandbar, were checked by ambulance volunteers.
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