The Danger Zone

The warnings are clear on many nautical charts, but when mariners read the caption “Danger Unexploded Ordnance,” it can be difficult to imagine what really happened in our very own Gulf of Mexico between Marco and Key West…and what still lingers today in the depths of a true Danger Zone. 

In 1942, Germany and Japan were at war with the United States. After the attack on Pearl Harbor, the War in the Pacific was the Japanese theater of aggression, but Germany brought World War II to the American coastlines and into the Gulf of Mexico.

Valuable cargo was steaming down the Mississippi and into the Gulf, and oil and gasoline tankers were cruising from Texas and bound for the Atlantic Ocean. The German naval intelligence knew of these vital trade routes and promptly dispatched long-range ocean-going submarines into the Gulf of Mexico. The U-boats came from the occupied French coast and after a week at sea, the submarines were on the prowl in the Gulf, and the results were devastating.

During the month of May in 1942, six German submarines sank 25 Allied ships in the Gulf of Mexico. The total number of ships sunk in the Gulf for 1942 was 56, and German war archives now show there were 10 U-boats operating in the Gulf in May of 1942. Sea mines were set to combat the catastrophic intruders, and throughout the shifting sands of a reclusive seafloor, some of the mines, unexploded depth charges, and shipwreck munitions still linger. 

Recreational scuba divers reported finding a tangle of unexploded military ordnance just after Hurricane Ike roared past the Florida Keys. Soon afterward, explosive ordnance divers came to explore the reports, but the arrival of another tropical storm made diving conditions unsafe.

After the subsequent storm, the investigating diving team returned to the Danger Zone but did not find any evidence of the reported mines or shipwrecked ordnance. The divers explained that whatever rose to the surface of the seafloor during one storm could easily sink beneath the sand during another weather event.

Navel historians are aware of many similar reports but give a warning to all adventure seekers. “Given the amount of mines out there from World War II, it would not be uncommon to find unexploded ordnance, but do not touch anything that resembles a mine or shell casing!”

For many years, much of the regional shrimping industry was operating between Key West and Ft. Myers Beach. After stone crab season was over for the Marco and Naples area, and the crab traps and the floating buoys were ashore for summer, shrimp boats would often lower trawling nets closer to the coast.

The shrimpers knew about the warnings on the charts, and they knew about the scuba diving rumors, but the shrimping in the “Danger Zone” was always the best.

A retired shrimp boat captain was happy to recall the antics of dropping shrimping trawls in the Danger Zone area. “Everyone knew about the old mines and knew they were there,” the captain related, “But the shrimping in those waters was really good - we just couldn’t resist.”

During the 1980s and even into the 1990s, it was not usual to snag a mine. Whenever the shrimp nets were overboard and trawling, a snagged mine was instantly obvious when a 90-foot shrimp boat suddenly began pivoting sharply toward whichever net had caught the mine.”

“The first time it happened, everyone onboard began freaking out,” said the retired shrimp boat captain. “We knew what we had as soon as the thing surfaced, and we immediately called the Coast Guard. After transmitting what happened, the Coast Guard radioed back and said: ‘Do not bring the mine into Key West - we will come out and get it!’”

“During one particular summer, and after an early hurricane, mine snagging became common. For whatever reason, many of the shrimpers in the Danger Zone began catching the big derelict mines. All the mines were really old and rusty. Some were of the type that had spikes sticking out and some looked like the head of a missile.

On one occasion, we hauled a mine aboard and set it down - gently. When it rested on the deck, it cracked open and began to leak a green, jelly-like liquid. Most of the old bombs were about five feet around and weighed about a thousand pounds.

After we had snagged a few and were confident they were not going to explode, we began to haul them out to a place we started calling the ‘The minefield.’ This was an area with a rocky seafloor where nets would snag on the rocks. For most shrimpers, this was a place to avoid, but who knows what hurricanes have done with those relics from the war.” 

During the war, when the German U-boats were having success in the waters off Key West and the Old Bahama Channel, Ernest Hemmingway apparently loaded his personal yacht Pilar with machine guns, grenades, and a bazooka and went U-boat hunting. The best chance of catching a U-boat on the surface was when a submarine was in shallow water and could not submerge. According to Key West legend, Hemmingway and his crew aboard the Pilar once sighted a German submarine, but before the Hemingway yacht could approach, the U-boat made a dive into deep water.

Throughout the history of warfare, no battlefield mysteries can be more complex than those waiting to rise from the seafloor. The Second World War was indeed a world event with the mechanisms of destruction creeping into every venue possible, but even in the peaceful waters surrounding paradise, the relics of a nautical Danger Zone remain as a reminder of a nearby naval history.