WASHINGTON (REUTERS) - The wreck of the US steamship Robert J. Walker, which sank in a collision with a schooner more than 153 years ago, has been identified off the coast of New Jersey, the National Oceanic and Atmospheric Administration said on Tuesday.

The Walker, built in 1847 as one of the first US government iron-hulled, side-wheel steamers, sank in rough seas on June 21, 1860, after being hit by a commercial schooner.

The 40-metre vessel sank within 30 minutes, taking 20 sailors down with it of a total crew of 66.

"Many of the men were doubtless washed off the spars and drowned from the mere exhaustion of holding on, while others were killed or stunned on rising to the surface by concussion with spars and other parts of the wreck," the New York Herald wrote in 1860, reporting the Walker's loss.

Resting 26m underwater near Atlantic City, the wreck was discovered in the 1970s by a commercial fisherman and has become a popular destination for divers, but its identity was not confirmed until June 23 of this year.

The Walker was a survey ship and was returning to New York from a mission to chart the Gulf Coast in the year before the Civil War. The work was part of the US Coast Survey, a precursor to NOAA's Office of Coast Survey.

"In 1860, as the Civil War approached, the Coast Survey redoubled efforts to produce surveys of harbors and strategically important to the war effort along the Gulf and Atlantic Coasts," NOAA said.

More information about the Walker is available online at http: www.nauticalcharts.noaa.gov/RobertJWalker/