Missing for 95 years, wreckage of the Navy tugboat Conestoga is found off California coast

It was the biggest air and sea search in U.S. history — at least until Amelia Earhart vanished in 1937.

The Navy was mystified as to the whereabouts of the U.S. tugboat Conestoga and its crew of 56, weeks overdue for arrival at Hawaii’s Pearl Harbor. The tug had departed Mare Island on March 25, 1921, and was last seen steaming away from San Francisco Bay.

Now, 95 years after it was lost at sea, authorities announced Wednesday that the Conestoga’s wreckage lies at the bottom of a marine sanctuary off the California coast near San Francisco.

The tug was only three miles off Southeast Farallon Island and a day out of port when it sank and its entire crew was lost, according to officials. The boat now rests at the bottom of what is now the Greater Farallones National Marine Sanctuary, according to the National Oceanic and Atmospheric Administration.

The Conestoga was expected to arrive at Pearl Harbor on April 5, 1921. However, the Navy really didn’t take notice of its absence until mid-May, NOAA officials said.

Authorities assumed it had vanished somewhere off the Baja California Peninsula, or close to Hawaii, but it turned out the Conestoga’s fate was sealed much earlier in its journey — probably by the same kind of rough seas that had sunk five other ships between 1858 and 1907 in the same area where it was found.

NOAA officials now figure that the choppy seas and the steamship’s reputation as a “wet vessel,� prone to take on water, led to its demise. It appeared to be trying to find calmer waters near Southeast Farallon Island when it sank.

“This would have been a desperate act: the approach is difficult and the area was the setting for five shipwrecks,� NOAA said in describing the find. “However, the Conestoga was in trouble — and this may have been the only choice to make.�

Like a police cold case, clues to unraveling the mystery of the Conestoga started with someone dusting off evidence and giving it a second look.

In 2009, sonar from NOAA’s Office of Coast Survey in the Greater Farallones sanctuary detected an object on the sea floor, but the images were fuzzy, the agency said.

It wasn’t until five years later, when the National Marine Sanctuaries Maritime Heritage Program investigated the sonar readings in 2014, that authorities realized what they’d found.

Three diving surveys of the sonar target revealed it was a 170-foot-long, World War I-era, steel-hulled, steam-powered ocean-going tug, NOAA said. After comparing the boat’s physical description with vessels that left the Golden Gate and were never seen again, authorities determined that it was the Conestoga.

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For the Record

March 23, 3:47 p.m.: An earlier version of this article implied that the Conestoga passed under the Golden Gate Bridge. The bridge did not yet exist.

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The shipwreck is now marked and protected by the National Marine Sanctuary Act and the Sunken Military Craft Act, NOAA said.

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