Most people who walk North Beach at Fort De Soto are thinking about the tide, not the ground beneath it. Few know that the sand they're standing on was once a target.
In 1940, the Army designated Mullet Key a bombing and gunnery range. The county, which had owned the land for barely two years and hoped to turn it into a park, sold it back to the federal government the following June for $18,404. For the next several years, Mullet Key served as a classroom for war, a place where pilots and air crews learned, under controlled conditions, what they would soon be doing over the Pacific and Europe.
At what's now North Beach and the Arrowhead Picnic Area, crews dropped sand-filled practice bombs onto marked targets. The east beach and the water beyond it saw the same kind of work. A separate stretch served as a target for aerial machine gunners running strafing passes low over the sand. On Bonne Fortune Key, one of the smaller islands that make up the park today, the training stopped being theoretical entirely: live bombs were dropped there, not just dummies.
When the war ended, the Army cleaned the site to the standards of the time and sold it to Pinellas County in 1948. Fort De Soto Park was dedicated in 1963. For decades afterward, the key's wartime service became little more than a footnote, a line in the timeline between “fort abandoned” and “park opens” that was easy to skip on the way to the beach.
The Army never fully stopped thinking about it. Land used for live ordnance training doesn't get a clean bill of health just because the lease ends. In 1986, the Department of Defense created the Formerly Used Defense Sites program, tasking the Army Corps of Engineers with returning to old military land across the country to determine what, if anything, remained. Mullet Key Bombing and Gunnery Range was one of roughly 700 such sites in Florida alone.
The Corps' Jacksonville District began its modern investigation of the site in September 2013. Contractors spent weeks marking out search areas, clearing brush, and sweeping the ground with digital metal detectors, looking for buried metallic objects that might be munitions left over from the war. It was deliberately unglamorous, methodical work, formally known as a Remedial Investigation and Feasibility Study, the first real step toward determining whether anything dangerous remained and what needed to be done about it.
Frank Araico, the Corps' project manager, was blunt about the stakes. Munitions that old don't come with an expiration date, and the team treated every find as a real possibility until proven otherwise. There's “always the possibility we could find something live, something still functional,” he said.
The investigation had to move carefully, and not just because of what might be buried. Fort De Soto's loggerhead sea turtles nest on the same beaches that once served as bombing targets, so the Corps brought biologists into the planning from the start. Susan Burtnett, a contractor on the project, said the team had “worked really hard to incorporate... a concern for the environmental resources,” clearing brush and running detectors without undoing decades of conservation work in pursuit of decades-old hardware.
The investigation never treated the whole key as one undifferentiated risk zone. The training had been specific, so the search was too. North Beach and Arrowhead Picnic Area, where the practice bombs fell, were handled differently than the stretch of Bonne Fortune Key where live ordnance was used. The east beach and its adjacent water got their own attention, separate from the area used for machine-gun strafing runs. The distinction matters more than it might seem. A practice bomb is typically inert or low-explosive, built to mimic the ballistics of a real weapon without the same payload. A live bomb is exactly what it sounds like, and knowing which beach was used for which kind of training is the difference between a sweep that's genuinely thorough and one that's just for show.
This isn't ancient history in the way the Narváez landing or the Seminole internment are ancient history. The Corps' investigation into Mullet Key wasn't a closed file from a hundred years ago. It was a federal environmental program actively doing fieldwork on this island within the last decade and a half, working through a process that's still unfolding.
It's also a reminder of how much a place can hide its own past. Fort De Soto's beaches have been ranked among the best in the country. They've been rebuilt and renourished, covered in new sand pumped in from offshore, smoothed over by tide and tourism for years. None of that erases what the ground underneath went through. The next time you're standing on North Beach watching the sun go down, it's worth knowing what that sand has seen.