The German U-boat, U-1105, a modified Type VII-C German submarine, was sunk in 90 feet (27 m) of water in the Potomac River at Piney Point. The sub was built in 1944 at the Nordseewerke Shipyard at Emden, Germany. It was launched April 20, 1944 and commissioned into the Kriegsmarine on June 3, 1944. It was an experimental design. It was one of 10 or fewer German Type VII-C submarines outfitted with a synthetic rubber skin (Alberich) designed to counter Allied sonar dvices. The coating absorbed sonar signals instead of reflecting them back to Allied ships in that "ping, ping, ping" sound familiar to anyone who's watched a submarine war movie. This sub was nicknamed "Black Panther" from the color of the synthetic material.
In its only mission of the war, in March of 1945 the submarine sailed from Wilhelmshaven for Kiel. It took on provisions, fuel, and ammunition and torpedoes, and in early April sailed from Kiel to Norway to conduct final testing and crew training before setting out on patrol. From the south coast of Norway, U-1105 set a course for the west coast of Ireland, eluding Allied air patrols, sub chasers equipped with ASDIC, and at least one large English minefield along the way.
The "Black Panther" patrolled off the west coast of Ireland from 6,600 feet (2,000 m) away, in Black Rock, hunting along the Allied convoy routes. The submarine’s commander was a 25-year-old lieutenant named Hans-Joachim Schwarz. On April 27, 1945, it found three British destroyers. The U-1105 fired two acoustic torpedoes. The destroyer escort HMS Redmill, a 1300 ton TE Captain Class frigate, was struck, although not sunk, and 32 men were killed. Allied ships searched for the "Black Panther" without success. The killer submarine dove to 330 feet (100 m) to escape a counterattack, laying silent on the bottom, cloaked in its black suit and remained undetected by the Allied search that ensued. It survived 299 depth charges in 31 hours, as counted by its crew. The U-1105 resumed patrol for one week until May 4, when the crew received a radio order telling them that the war was over. The submarine was ordered to an Allied base in northern Scotland where it surrendered to the British.
The U-1105 was turned over to the U.S. Navy for study, testing and experimentation with a new depth charge. It took the U-boat 16 days to sail from England to the United States. During the transfer, the U-1105 encountered very heavy seas. By the time it reached its destination at the Navy Yard near Portsmouth, VA, much of the U-1105's rubber coating had been torn loose and lost – the primary reason the Navy wished to acquire the vessel.
Research on the remainder of the rubber skin of the "Black Panther" began in early 1946. It was damaged and sunk on September 19, 1949 in 20 seconds by a Navy Explosive Ordnance Disposal team, settling into its final resting place a mile offshore at the bottom of the Potomac River. For more than thirty years, the U-1105 lay lost to history. Mistakes in archiving the coordinates of the site resulted in the boat being lost. When the Navy recorded its location, someone transposed its longitude figures from 76 degrees west to 67 degrees west. That put the sunken submarine several hundred miles into the Atlantic Ocean in water too deep for divers.
Years after a Navy disposal team sank the sub, in June of 1985, it was "rediscovered" by a team of recreational divers from Virginia led by Uwe Lovas, who figured out the mistake after seeing a photograph of the final explosion. Land was in the background; the U-1105 couldn't be several hundred miles out to sea. However, an unidentified shipwreck was offshore at Piney Point, longitude 76 degrees west. That turned out to be the "Black Panther".
In 1992-93, with support from the St. Clement’s Island-Potomac River Museum, the Maryland Historical Trust, and Sea Colony Aqua Sports, the site became the subject of an archeological survey expedition. Supported by financial assistance from the Department of Defense Legacy Resource Management Program, and a cooperative agreement between the Navy and the State of Maryland in 1995, the U-1105 wreck was designated as Maryland's first historic shipwreck preserve. The preserve is intended to promote the preservation of historic shipwreck sites while making them accessible to the general public.
The site is now marked with a mooring buoy. At most times of the year, the only visible portion of the U-1105 is the conning tower. The lowest point of the wreck is at a depth of 91 feet, the shortest point is at a depth of 65 feet in near-zero visibility with a swift, constant current. Visiting the wreck is discouraged, as it is considered an advanced dive. Divers must register the dive with the Maryland Historical Trust first, and follow specific safety guidelines.