The sound was muffled but the source familiar. Rap an air tank with a knife—it was the same bell-like sound. It told me at least one man was alive. No . . . they were both alive, I realized. I was now hearing a duo of bell sounds: Tomlinson and Will both banging on their tanks.
Tomlinson didn’t carry a knife—it was irrational, but he never did—so he must have been using a flashlight or a D ring from his vest.
The clanging was steady, not frantic, which I found reassuring. My partners were trapped somewhere under the crater floor, beneath a plateau of rock and sand, but obviously they had room enough to move their arms. It suggested that they were in a crevice or in an underground chamber that had been covered by rubble
I unsheathed my knife and began to dig methodically, pulling away rock, digging at the bottom. It was mostly sand. Frustrating. Digging a hole underwater is an exercise in futility. If I scooped out two handfuls of sand, twice that amount sieved downward and filled the temporary hole. Thinking it might be more efficient, I grabbed a pan-sized oyster shell and used it like a shovel.
It wasn’t much better. Until I returned with the jet dredge, though, a shovel was my best option. I continued digging, burning my dwindling air supply, until the clanging signal from beneath the crater changed. It caused me to pause.
I heard an articulate TAP. Tap-tap-tap . . . TAP . . . tappa-tap. Over and over, with the same careful spacing. Some sounds were intentionally louder, it seemed.
I banged the oyster shell against my own tank, parroting the signal . . . then received a different signal in reply.
Tap . . .TAP . . . tap.
It was Tomlinson. Had to be. Tomlinson, the blue-water sailor, the maritime minimalist. He was attempting Morse code. The man had been studying code for nearly a year, inspired by a late, great friend who had railed against our growing dependence on technology.
I’ve been a devoted user of shortwave radios since childhood, but I’m not a student of Morse code. I know a few basic shorthand signals, but now was not the time to test my skills. We had less than twenty minutes of air left. Subtleties of communication would have to wait.
I returned to my digging, bulling chunks of limestone to the side, then using the oyster shovel to scoop a dent in the sand. I kept at it until a sound within the wall caused me to pause once again.
It was an alarm sound, the rapid clang-clang-clang of a fire bell. Tomlinson was telling me to stop digging.
Why?
I could think of only one possibility: My digging was somehow threatening the stability of the space that was providing them refuge.
Maddening! If I couldn’t dig, how did Tomlinson expect me to free them? After several seconds of silence, he tried Morse code again.
Tap . . .TAP . . . tap.
I forced myself to concentrate. The louder clanks, I decided, were dahs in Morse. The faster, lighter raps were dits.
Tap . . .TAP . . . tap.
Was it the letter R? Yes, an R. R is the most common Morse abbreviation. Even I recognized it. R stands for “roger”—“signal understood.”
It was Tomlinson’s way of beginning a dialogue.
I attempted a dit-dah-dit reply, then waited.
Once again, he tried to signal, but the letters wouldn’t take shape in my head. Because I didn’t understand, I let silence communicate my confusion.
Tomlinson tried a different pattern. I heard: Dit-dit . . . DAH . . . dit. DAH . . . dit-dit-dit.
Three times, he sent it, before I recognized another common Morse abbreviation. F-B. It was short for “fine business”—the equivalent of “everything’s okay.”
Everything was certainly not okay. He was telling me they weren’t hurt—not seriously, anyway. So why had he sounded an alarm?
I tapped out the letter R in reply—“understood”—then listened to a string of louder, methodical bell notes. Instead of attempting to translate, I counted . . . counted four distinctive clangs, but the fifth—if there was to have been a fifth—was interrupted by a cascading clatter of rock and then a thunderous thud.
Another section of lake bottom, or possibly the interior wall of the crater, had collapsed—loosened by our clanging sound waves, more than likely.
I was blinded by another silt explosion, but this time I held my ground. I hung tight to a wedge of rock as the murk enveloped me. For a full minute, I waited for the unstable limestone to settle before I attempted to signal Tomlinson again.
This time, when he replied, the sound was much fainter. Either more sand and rock separated us or his location had changed.
I didn’t want to risk another exchange in Morse code. Sound waves are corrosive, and the lake bottom was too unstable. I needed the jet dredge.
A dredge is the underwater equivalent of a pressure washer. The one we had brought consisted of a generator, a heavy coil of hose that floated on a tractor-sized inner tube and a brass nozzle fitted into a three-foot length of PVC pipe. The thing shot a laser stream of water that would cut through rock and sand and was commonly used for setting pilings—or for treasure hunting. That’s why we’d brought it.
I had to get the generator going, prime the pump and return with the hose. I needed Arlis Futch’s help.
On the chance that Tomlinson and Will had, in fact, found refuge in an underground chamber, I located a crevice below the crater. It took a while to find one that looked to be about the right size. Without removing my BC, I popped a latch on the backpack, freed my air bottle and pulled it over my head. After I had inhaled a couple of deep breaths, I closed the valve, then purged my regulator before removing the pressure gauge and regulator hoses.
Full air bottles sink. Empty tanks float. Mine was half full, so it was easy to maneuver. I wedged the bottle into the crevice, valve up, and braced it with a chunk of rock. When I was convinced the tank was secure, I opened the valve a quarter turn.
A silver chain of air bubbles ascended from the tank. They began to disperse along the underside of the crater. The bubbles became as animated as ants as they probed the rock face, seeking vents and passages to continue their ascent. If there was a chamber above, the bubbles would find the open space and burst free.
I am not a cave diver, although I had explored a couple of caves years ago beneath an island off Borneo. But I’ve spoken with, and read about, Florida’s cave divers—an exacting, dedicated group that has lost more than one comrade to their collective passion for mapping subterranean labyrinths.
From these people, I had acquired a sense, at least, of the complex geology that defines the underwater karst catacombs that exist beneath the flatlands of central Florida. A small rock vent can lead to an ever-narrowing dead end, but it might also open up into a cavern. Caverns have been discovered beneath Florida’s flatlands that are the size of airplane hangars, vaulted cathedrals of limestone. Some were formed during the Pleistocene and had once been home to wandering families, human and animal, before the rising sea level flooded them.
I had heard that such caves might contain air bells—pockets of air—although I doubted the truth of it. Not in Florida, anyway. An airtight vault in rock as porous as limestone? It was unlikely.
Even so, wedging a bottle beneath the collapsed ledge was worth a try. Maybe, just maybe, Will and Tomlinson had been lucky enough to find an air pocket. Maybe, just maybe, I had provided my friends with additional air.