Divers Discover the Shipwreck of a World War I-Era Coast Guard Cutter, Which Vanished With 131 Sailors on Board in 1918

Steve Mortimer tempered his expectations before he slipped beneath the surface of the Atlantic Ocean. As he dove, the light from above faded, and the readings on his depth gauge crept past 300 feet.

“It gets darker and darker,” he recalls. “Eventually, out of the gloom, the seabed appears—or, if you’ve done it right, the shipwreck appears.”

Mortimer, the leader of the British technical diving team Gasperados, was searching for the Tampa, a United States Coast Guard cutter that sank in 1918. A German submarine torpedoed the vessel, killing all 131 people on board—the largest single loss of life in American naval combat during World War I. The Tampa’s final resting place had long been a mystery.

These kinds of cases are Gasperados’ specialty. “We look to solve mysteries,” Mortimer says. “We turn up where we think there’s a good story to be told.” For three years, the team worked with historians to comb through the archives for clues. They ultimately identified ten sites to investigate.

The first nine dives were a bust. Then, on April 26, the team conducted the final dive about 50 miles off the coast of Cornwall, England. When the divers reached the seabed, they saw wreckage that looked an awful lot like a warship.

The six men had only a short time to document the wreck before they returned to the surface. Because the human body needs to slowly adjust to pressure changes, that ascent took more than an hour, leaving them plenty of time to reflect on what they’d found.

A video from that day shows diver Dominic Robinson emerging from the water and stepping onto the boat. “Well, Dom, you’ve just come up from 95 meters, two and a half hours,” an off-screen voice asks. “What did you see?”

As he removes his gear, Robinson lists off everything he can remember: Portholes. Ammunition. A “most immaculate” set of bridge gear. An anchor that matched historical photographs.

“I’ve been thinking about it all the way back up,” he says. “On the balance of probability, I think that is probably the Tampa.”

USCG Tampa FOUND: America’s Deadliest Coast Guard Disaster

The history of the Tampa

The Coast Guard’s history stretches back to 1790, when George Washington signed legislation authorizing the construction of ten vessels to enforce trade laws. But its current name dates to 1915, when the Revenue Cutter Service merged with the Life-Saving Service. Two years later, when America entered World War I, six Coast Guard cutters were sent overseas, where they were tasked with protecting convoys from submarine attacks. All but the Tampa would return.

“The service has lost quite a few ships and a lot of personnel in its 235-year history,” says William Thiesen, the Coast Guard’s Atlantic area historian. “This one was one of the most important.”

Over 11 months, the 190-foot-long vessel escorted 18 convoys from Gibraltar to Great Britain. Its logs reveal “high morale, in spite of rather grueling duty,” the Coast Guard notes on its website. Records show the men quickly coming to the aid of sailors from other vessels; in one case, two stewards even “got into trouble for being too helpful” when they allowed another ship to borrow an ice cream freezer.

On September 26, 1918, the Tampa was running low on coal. Its captain, Charles Satterlee, asked for permission to leave the convoy and load up at around noon. Because sailing alone in the daylight was dangerous during wartime, this request was denied. A second request was approved at 4 p.m.

Hours later, the Tampa traveled north through the moonless night. The crew had turned off all lights to avoid detection. Despite these precautions, a German U-boat skipper spotted the vessel in the Bristol Channel. A few miles away, a radio operator reported that he’d felt an underwater explosion. The Tampa never arrived at its destination.

Everyone aboard the vessel—111 U.S. Coast Guardsmen, 4 U.S. Navy personnel, and 16 British Navy personnel and civilians—died in the attack. “Quantities of wreckage, one of the Tampa’s lifebelts and the bodies of two unidentified officers in uniform were found,” the Associated Press reported at the time. A third body surfaced later, but the rest were never recovered.

The search for the Tampa

As the Gasperados divers prepared for their tenth attempt to find the lost cutter last month, they weren’t sure what to expect. “It was the last one within the foreseeable area that could possibly be the Tampa,” Robinson recalls in the video. “But in my mind, this was more of a box-ticking exercise than anything else.” After he dove in, he realized that his GoPro camera wasn’t working. Not expecting the dive to amount to much, he hadn’t checked it beforehand.

The divers are all volunteers, most based in southwest England. They’ve found a number of other missing shipwrecks from World War I over the years, and they had long known about the Tampa. In 2023, they decided to start looking for it.

Historian Michael Lowrey, an expert on German U-boats in World War I, helped the divers track down archival records. The group also contacted historians at the Coast Guard, who shared information about the Tampa’s unique features, which would later help confirm the wreck’s identity.

“We sent virtually everything we had,” Thiesen says. “Imagery, blueprint schematics—any kind of design or construction information that would lead them to cross reference with the items they’re finding on the seafloor.”

That information was critical given how little time the divers had to explore the seabed. Mortimer estimates that he spent just 14 minutes at the site. But even with these constraints, the team found a wealth of compelling evidence. They noticed artillery shells covering the seafloor that looked like they could match the vessel’s guns. One diver made out the words “Trenton, New Jersey,” on the back of a plate. The team also identified an anchor, fire extinguishers and portholes that matched the archival records.

“Tampa was a relatively small ship, but she had lots of portholes,” Mortimer says. “Now, lots of the hull has rotted away, but because portholes are often made of brass, they’re still there and they’re intact. There were lots of these portholes just lying around the place.”

The divers also found a water-tube boiler—the same type installed on the Tampa. “That says almost definitively, I think, it was a warship,” says Barbara Mortimer, a researcher for Gasperados and Steve Mortimer’s wife. In contrast, merchant ships tended to have fire-tube boilers, which are “more economical, but they heat up the steam more slowly, so you can’t accelerate as fast,” Barbara adds.

The divers plan to return to the wreck site soon to search for more evidence. According to Thiesen, once the vessel’s identity is confirmed, the site will be treated as a war grave.

“We saw at least two fire extinguishers on the wreck, and one of our divers thinks that he saw Tampa written on it,” Mortimer says. “We are hoping to take photographs of that, which obviously will be absolutely conclusive proof.”

The Tampa’s legacy

A week after the disaster, the Coast Guard sent out telegrams to the families of the victims, many of whom had been in their late teens and early 20s. The youngest was 15-year-old Irving Alexander Slicklen. Because he was tall for his age, he had managed to enlist after school one day. When Slicklen’s great-grandmother learned what he’d done, she raced to the recruiting office in her bed slippers, but she was too late. He died after serving for only six months.

Joseph Lieb, 18, had been expecting to return home soon, and his family was already planning a celebration when they heard the news. The father of Edward F. Shanahan Jr., 21, had written his son a letter wishing him luck in his new enlistment; according to the Washington Post, it was returned unopened with the words “Man Lost” stamped on the front.

The disaster was devastating for the Coast Guard, whose ranks numbered fewer than 4,000 men at the beginning of World War I. The U.S. Navy, in comparison, had more than 50,000. As a result, the agency experienced a higher percentage of casualties than any other branch of the American military during the conflict.

“When the Tampa was lost with all hands in 1918, it left an enduring grief in our service,” Kevin Lunday, commandant of the Coast Guard, says in a statement. “Locating the wreck connects us to their sacrifice.”

The Purple Heart wasn’t in use at the time of the disaster, but the Coast Guard awarded it to the crew of the Tampa in 1999. For many years, officials have been trying to reach the men’s families to present them with the honor.

Since the discovery was announced, several of those families have reached out to the divers. Some said they knew their relatives had died on a ship called the Tampa, but they’d always wondered where its wreckage was. After all this time, they were happy to learn the answer.

“We’re really pleased to have done it. It justifies all our effort and hard work,” Mortimer says. “We’ve dedicated three years of our lives to try to find this ship because it’s important to us—and we know it’s important to other people.”

Although shipwreck hunting is a hobby for the Gasperados divers, they see their work as an important form of citizen science, as well as a tribute to the victims. “Their final resting places need to be known, and their stories need to be told,” Mortimer says. “That’s why we do it.”