Alaska ? A private dive team has discovered the wreckage of an American ship that sank off the south-central Alaska coast 139 years ago.

The Torrent sank in Cook Inlet in 1868 after tidal currents rammed it into a reef south of the Kenai Peninsula. Documents from the period show that all 155 people on board survived.

The U.S. had purchased Alaska from Russia less than a year earlier, and about 130 Army soldiers had come north on the Torrent to build the first U.S. military fort in south-central Alaska.

The shipwreck is the oldest American wreck ever found in Alaska.

A four-man dive team led by Steve Lloyd, owner of Anchorage’s largest independent book store, found remnants of the wreckage in July. They kept the discovery secret at the request of state officials, who wanted more time to document the site before any looters arrive. Its discovery was announced Monday.

An array of objects, from guns and cannons to shoes and plates, are hidden beneath the broad leaves of giant kelp beds or concealed in caverns and crevices among massive boulders, Lloyd said.