Marvin Barrash, of Kent Island, shows the displays he made with photos of the lost USS Cyclops. The Navy ship vanished 100 years ago with 309 men aboard, and it remains the greatest loss of life unrelated to combat in U.S. Navy history. (Tim Prudente / Baltimore Sun)

There should have been a clue: a distress call on the radio, a shard of wooden lifeboat, even a sailor’s cap. How could 309 men and their ship, a naval vessel bigger than a football field, just vanish?

One hundred years ago Tuesday, the USS Cyclops was due to steam up the Chesapeake Bay and dock in Baltimore at what is now Port Covington.

The ship still hasn’t shown up.

…“In terms of loss of life and size of ship, it’s probably the last great mystery left unresolved,” said James Delgado, the renowned underwater explorer.

Read the full story by Tim Prudente on the Baltimore Sun website here.