The decommissioned U.S. Navy Virginia-class submarine was taken out of service in 2013 and mothballed for nearly 18 months before ownership was transferred to the Hamptons Police Department.

"I want to emphasize that this submersible craft came at no cost to taxpayers," Hamptons PD representative Larry Hirsch explains in a press release. "With the blessing of the Hamptons Municipal Board, we requested such a watercraft last year under a federal program to outfit local police departments with surplus military equipment."

Aimed mainly at counter-narcotic and counter-terrorism operations, this military grade gear—such as heavily armored MRAP vehicles, automatic weapons and body armor—was initially handed out to police departments in border towns and those with serious crime problems. But the need has grown drastically around the country in recent years, and smaller departments in seemingly "safer" areas are getting in on the action.