A diving expedition in the Gulf of Mexico just south of the Mississippi River has produced stunning new images of one of Hitler's U-boats from World War II.

Some people might be surprised that the Nazis got so close to American soil.

On July 30, 1942, a U.S. Navy* escort vessel destroyed the U-boat, U-166, after it attacked and sank the SS Robert E. Lee about 25 miles southeast of the mouth of the Mississippi. The Lee, a freighter, was delivering hundreds of survivors of other U-boat attacks to New Orleans. Twenty-five passengers and crewmen aboard the ship were killed. Another 404 survived. The German submarine was sunk with no survivors. Its wreck is protected as a war grave for the 52 crewmen who died. Both vessels lie about 5,000 feet below the surface.

"Most people don't realize that during World War II, America really was under siege," National World War II Museum curator Tom Czekanski told WWLTV.

The new images of the sub and the freighter were captured by an underwater expedition led by Dr. Bob Ballard of Ocean Exploration Trust. Ballard is perhaps best known for being credited with discovering the wreck of the Titanic.

"Hitler brought the war to our doorstep shortly after they declared war on us," Ballard said.

"Over 20 U-boats operated in the Gulf of Mexico and over 70 ships were sunk off the Gulf of Mexico in 1942 and 1943," Czekanski said.

Ballard's team, aboard the Exploration Vessel Nautilus, was conducting forensic archaeological documentation and surveys of the U-boat and related shipwrecks to better understand how they met their fate. Many of these wreck sites have not been documented in any detail, so the team on board conducted high resolution mapping in addition to visual surveys to create 3-D images of the wreck sites for further analysis.

* This story has been updated to reflect the following correction: The Nazi submarine U-166 was sunk in the Gulf of Mexico on July 30, 1942, by the Robert E. Lee's escort ship, USS PC-566, which was a U.S. Navy vessel. Historical accounts included in an earlier version of this story incorrectly credited the Coast Guard.