On the floor of the Gulf of Mexico lies a Nazi ship of ghosts... evidence of how close World War II came to the shores of Texas.
It's a story most Americans never knew.
'And there's a very good reason,' said shipwreck diver Richie Kohler. 'The United States government didn't want us to know. They didn't want us to know how Germany was taking us to task, how successful these U-boats were.'
Nazi propaganda films trumpeted the triumphs of Hitler's U-boats, submarines that sank thousands of Allied ships primarily in the North Atlantic.
But there's another story undocumented by films archived on the Internet. Nazi naval commanders dispatched 22 U-boats to prowl the Gulf of Mexico, including the Texas coastline.
For the past 10 days, Robert Ballard, the underwater explorer who discovered the Titanic, has been searching shipwrecks that U-boats left behind along our Gulf Coast.
'Hitler brought the war to our doorstep shortly after they declared war on us, so this was something that most American people do not realize: How close the war came, and how threatening it was,' Ballard said. 'They were extremely successful.'
Historians say U-boats sank at least 50 American ships in the Gulf, one in the very mouth of the Mississippi River.
Americans managed to sink only one U-boat in the Gulf of Mexico.
'It is a static time capsule, and all of these shipwrecks in deep water are just that. They're moments frozen in time... in history,' Ballard said.
And they're a ghostly reminder of a time when Hitler's navy came startlingly close to the shores of Texas.