New charges have been levied against five so-called urban explorers accused of flooding and partially sinking a World War II-era submarine in New Jersey during a pair of break-ins last summer.

Criminal counts of conspiracy and knowingly causing a flood were added on top of the burglary and criminal mischief counts already in place, according to an indictment from July 9 reported by NorthJersey.com.

Jon Stevens and Laura Palmese of Connecticut; and Edward Johnson, Stacey Bouley and Robb Hemberger, whose home states were not immediately known, were arrested in connection with the alleged vandalism and burglary. The five identify as urban explorers, people who visit abandoned structures for fun.

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The intruders boarded the 1,500-ton USS Ling in the Hackensack River, opened the underwater hatches and stole four bronze plaques honoring the more than 3,000 Navy officers who died on U.S. submarines during World War II, authorities said.

The vessel was flooded, police said. Several artifacts inside the submarine, including radio transmitters, uniforms and textiles, were lost due to water damage, said Gilbert De Laat, president of Submarine Memorial Association, which maintains the sub.

Police said the burglaries occurred during two visits, last July and August.

The Ling once served as the New Jersey Naval Museum’s centerpiece exhibit, but was closed in 2013 due to damage from Superstorm Sandy.

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The 312-foot-long vessel is a Balao-class submarine that was commissioned on June 8, 1945. It was the last of a fleet of boats that patrolled U.S. shores during the Second World War.

De Laat said there aren't any resources to relocate the submarine, which would cost hundreds of thousands of dollars.