DEME’s expertise reveals last German WWI submarine in Belgium

After many years of research, a mystery has finally been solved: the last unknown German submarine from World War I in Belgian waters has been identified as the UB-57. The wreck of the UB-57 lies near the French border, west of the Westhinderbank, at a depth of about 17 meters. Although the wreck had been known for over thirty years and even protected as maritime heritage, its exact identity remained unclear. The submarine is largely buried in the sand, which made the research challenging.

“The significant challenge we faced was that traditional dredging was not an option; instead, we had to carefully blow the sand away. The primary risk was the potential damage to the submarine, which we absolutely had to avoid. This required extensive soil research to determine factors such as the compaction and grain size of the sand. Using a water jet at reduced power (via the AMOB system), we meticulously cleared the stern of the submarine, which had been buried for over a century. This process exposed the propellers, which bore inscriptions that ultimately confirmed the submarine’s identity as the UB-57,” commented Dirk Defloor (Area Director Benelux for Dredging & Infra) on the discovery. “Thanks to the excellent collaboration between the crew of our ‘Meuse River’ and our EDT and Survey department, DEME was able to contribute to solving the mystery of the last unidentified German U-boat from World War I in Belgian waters.”

The wreck belongs to the UB-III type, an advanced submarine with a range of 9,000 nautical miles and heavy armament, including five torpedo tubes and an 8.8 cm gun. The UB-57 disappeared on August 14, 1918, after a patrol during which three more ships were sunk. The wreck of the UB-57 is not only of historical importance but also a war monument. All 29 crew members perished in the disaster. After identification, the wreck was carefully reburied under the sand to prevent further erosion and damage. 

The governor of West Flanders and chairman of Vlaams Instituut voor de Zee VLIZ, Carl Decaluwé, presented the discovery of the last unknown German submarine on April 14 at the InnovOcean Campus of VLIZ. Dr. Tomas Termote provided an explanation of this discovery in the presence of the German embassy, representatives of DEME, and the gathered press.

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