Routine scan of Gulf of Mexico seabed for new petroleum pipelines reveals shipwrecks.


During World War II, U-boats prowled the Gulf of Mexico to disrupt the flow of oil carried by tankers departing ports in Louisiana and Texas.

Today’s petroleum companies operating in the Gulf of Mexico’s outer continental shelf routinely provide government scientists with sonar data for areas with potential archaeological value. Federal agencies review oil and natural gas-related surveys, and over the years the data have revealed more than 100 historic shipwrecks in U.S. waters.

Circa early 2000s offshore oil industry sonar image and photo of U-boat in Gulf of Mexico.

A 2001 archaeological survey by BP and Shell prior to construction of a natural gas pipeline confirmed discovery of U-166 about 45 miles off the Louisiana coast.

In 2001, the Minerals Management Service noted that “a German submarine definitely got our attention.”

U-Boat Scourge

In the months following America’s entering the war, the Kriegsmarine sank 56 Allied ships, including 17 tankers, while losing only one submarine, U-boat 166.

German submarine attacks so threatened the war effort that American government and the petroleum industry responded with the longest pipeline project ever undertaken, building the “Big Inch” and “Little Big Inch” from East Texas to Illinois, and as far as New York. Learn more in WW II Big Inch and Little Big Inch Pipelines.

But for the U-166, the war was over. Its final resting place remained a mystery for almost 60 years.

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The last victim of the U-166 was the passenger freighter Robert E. Lee, sunk by a single torpedo on July 30, 1942, while on its way to New Orleans. Her Naval escort ship, PC-566, rushed in to drop ten depth charges. The U-166 was believed to have escaped. It did not.

Photo of WWII U-166 submarine from National World War II Museum.

Commissioned on March 23, 1942, U-166 today is a war grave in the Gulf of Mexico. Photo courtesy National World War II Museum.

Finding U-166

In 1986, a Shell Offshore vessel using a deep-tow system of the day recorded two close wrecks about 45 miles off the Louisiana coast in 5,000 feet of water. the identity of the vessels would surprise military historians.

At first thought to be the Robert E. Lee and cargo freighter Alcoa Puritan, it was May 2001 before an autonomous underwater vehicle (AUV) using side scan sonar revealed the U-166. The lost World War II submarine was separated from Robert E. Lee by less than a mile on the sea floor.

The AUV, which required no cable connection to its mother ship, found the Alcoa Puritan 14 miles away. Learn more about the petroleum industry’s offshore robotics in ROV – Swimming Socket Wrench.

Advanced underwater technology for seafloor mapping Illustration.

The U.S. petroleum industry remains a principle user of advanced underwater technologies for seafloor mapping. Illustration courtesy BOEM.

Six other World War II vessels have been discovered in the course of Gulf of Mexico oil and natural gas surveys.

As a result of the U-166’s discovery, BP and Shell altered their proposed pipeline to preserve the site and government archaeologists notified the U.S. Navy Historical Center of the discovery.

“They, in turn, notified the German Embassy and military attaché,” the MMS article explains. “Since the remains of the U-166’s 52 crewmen are still on board, the German government has declared the site to be a war grave and has requested that it remain undisturbed.”

Managing Offshore Oil

The Minerals Management Service in 2011 became the Bureau of Ocean Energy Management (BOEM) and the Bureau of Safety and Environmental Enforcement (BSEE), which also maintains offshore maps and statistics, including production summaries.

In early 2021, BOEM managed more than 2,200 active oil and natural gas leases on about 12.1 million acres of the Outer Continental Shelf.

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“Offshore federal production in 2020 reached approximately 641 million barrels of oil and 882 billion cubic feet of gas, almost all of which was produced in the Gulf of Mexico,” the agency noted. “This accounts for about 15 percent of all domestic oil production and 2 percent of domestic natural gas production.”

The Kerr-McGee drilling platform Kermac Rig No. 16 in 1947 became the first offshore rig in the Gulf of Mexico that operated out of sight of land. The Gulf’s offshore industry would discover 11 oil and natural gas fields by the end of 1949. Learn more in Offshore Oil History; also see Women of the Offshore Petroleum Industry.


Recommended Reading:  Torpedoes in the Gulf: Galveston and the U-Boats, 1942-1943 (1995); Offshore Pioneers: Brown & Root and the History of Offshore Oil and Gas (1997). Your Amazon purchase benefits the American Oil & Gas Historical Society. As an Amazon Associate, AOGHS earns a commission from qualifying purchases.


The American Oil & Gas Historical Society (AOGHS) preserves U.S. petroleum history. Become an AOGHS annual supporting member and help maintain this energy education website and expand historical research. For more information, contact © 2023 Bruce A. Wells.

Citation Information – Article Title: “Petroleum Survey discovers U-boat.” Authors: B.A. Wells and K.L. Wells. Website Name: American Oil & Gas Historical Society. URL: Last Updated: July 20, 2023. Original Published Date: April 18, 2012.


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