Coast Guard, this is motor-vessel Bonsai, we have a missing diver in the water. Repeat, missing diver.” I scanned the choppy water as we motored in increasing arcs, realizing the near-impossibility of spotting a person in the 7ft (2m) swells. I’d rehearsed this scenario in my head a hundred times, but nothing could prepare me for the sense of dread

I was feeling. I should have listened to that same sense when we were bouncing out to the wreck site with no other boats in sight. Now here we were, facing a search for one missing diver in a very big ocean with dusk falling and storm clouds piling up on the horizon. Training kicked in and I twisted the bezel of my Blancpain Fifty Fathoms to mark the beginning of our search and scanned the water for movement.

The Florida Keys are an archipelago of islands that curl off from the mainland United States like the tail of a kite. A series of shallow reefs sits just offshore and the Gulf Stream bathes them in clear, warm water. Forward-thinking government protection has kept the environment healthy and the reefs teem with countless species of colorful fish, as well as larger pelagics that cruise in from the deeper water between here and Cuba. It is a diver’s paradise and has been ever since the heyday of recreational diving in the 1960s. Driving down Highway 1, past low-slung motels and souvenir shops, feels much like it must have in those days, when divers discovered the wrecks and reefs offshore and flocked there by the thousands. No doubt many of them wore a no-frills, sturdy underwater watch with the evocative name “Fifty Fathoms”, from a small Swiss brand called Blancpain. Diving in the Keys feels historic and it was somehow appropriate to wear Blancpain’s modern tribute to their legendary dive watch during four days of diving there.

Training kicked in and Jason Heaton twisted the bezel of his Blancpain Fifty Fathoms to mark the beginning of the search and scanned the water for movement.

Training kicked in and Jason Heaton twisted the bezel of his Blancpain Fifty Fathoms to mark the beginning of the search and scanned the water for movement.

By now, most people know the history of the Fifty Fathoms, but it bears repeating. French secret-agent-turned-combat-diver Robert Maloubier sought a suitable dive watch for his newly formed team of Special Forces divers and approached Blancpain for help. They built a watch to Maloubier’s specification, with a unidirectional rotating timing bezel, large luminescent dial-markers and a case that was at least water resistant to a depth of 91 meters, or the more poetic-sounding 50 fathoms, a depth then thought to be the maximum a man could dive on air. The Blancpain Fifty Fathoms was released in 1953, the same year another famous dive watch made its debut: the Rolex Submariner. Which one came first is a question we may never answer, but the evolutions of each took different paths through the decades and both pioneers are still at the top of their class today.

The Florida Keys are not only known for their reefs, but also for numerous shipwrecks. Out of Key Largo, a trio of intentionally sunk ships, the Spiegel Grove, the Duane and the Bibb, are popular with divers due to their accessibility and abundant fish life.

The Florida Keys are not only known for their reefs, but also for numerous shipwrecks. Out of Key Largo, a trio of intentionally sunk ships, the Spiegel Grove, the Duane and the Bibb, are popular with divers due to their accessibility and abundant fish life.

Tropical storm Debby was playing cat-and-mouse with Florida for several days. The stiff southerly wind was whipping up whitecaps and big seas that left our small group feeling green on the ride out to the dive sites on day one. Of course, once underwater, all was serene and we enjoyed long bottom times on the shallow reefs before ascending for the rodeo ride on the boat. We played peek-a-boo with a hiding southern stingray on French Reef and sized up some monster goliath groupers over on Molasses. The weather was keeping other divers away so we enjoyed empty reefs.

The Florida Keys are not only known for their reefs, but also for numerous shipwrecks. Out of Key Largo, a trio of intentionally sunk ships, the Spiegel Grove, the Duane and the Bibb, are popular with divers due to their accessibility and abundant fish life. On our second morning, we descended the fixed mooring line on the USCGC Duane, a former Coast Guard cutter sunk in 131 feet (40m) of water. Contrary to the unfavorable surface conditions, the current on the wreck was light, and visibility infinite. Descending past the crow’s nest, we passed through a fleet of barracuda that hung motionless, their dead eyes following us ominously. On the wreck, a school of Bermuda chubs circled slowly around the derelict bridge while a giant grouper disappeared inside the engine room. We swam from bow to stern before ascending the line for a short decompression stop just below the waves.

Unlike the Rolex Submariner, which has remained largely unchanged over the years, the Blancpain Fifty Fathoms has seen countless iterations, with cases, dials and bezels mirroring the styles of the times in which they were produced. Undoubtedly one of the most popular models was the one produced in the late 1960s that was branded “Aqua Lung”, in reference to Cousteau’s game-changing invention. It was this model to which Blancpain chose to pay tribute with the limited edition I was wearing in the Florida Keys.

Instantly recognizable and often mimicked, the Tribute to Fifty Fathoms Aqua Lung features a domed sapphire crystal with minimal minute hashes and a diamond-shaped descent marker. The dial is spare, with only the lovely scripted “Aqua Lung” and “Fifty Fathoms” below the Blancpain logo. Painted markers at 12, three, six and nine o’clock hark back to the watch’s forebear and the hands are the same pointed, military style as Captain Maloubier would have demanded.

Unlike the Rolex Submariner, which has remained largely unchanged over the years, the Blancpain Fifty Fathoms has seen countless iterations, with cases, dials and bezels mirroring the styles of the times in which they were produced.

Unlike the Rolex Submariner, which has remained largely unchanged over the years, the Blancpain Fifty Fathoms has seen countless iterations, with cases, dials and bezels mirroring the styles of the times in which they were produced.

Unlike some similar recent Fifty Fathoms versions, the 45mm steel case has a completely brushed finish — in my opinion, a must-have feature of a military-inspired watch. Unlike the original, the luminescent paint used is non-radioactive SuperLuminova and may be the brightest, most legible watch dial I have ever used. The strap Blancpain fits to this noble tribute piece is a stitched textile with large rally-style holes that mimics the style of the Tropic rubber straps that would have held the original Fifty Fathoms Aqua Lung to divers’ wrists. Instead of an ordinary pin buckle, Blancpain has fitted a fold-over deployant with double push-button release. The clasp also includes a clever extension that folds in on itself and provides just enough extra room to slide the watch over your hand and easily fits over a 5mm wetsuit sleeve.

With the Tribute to Fifty Fathoms Aqua Lung, Blancpain has succeeded in creating a faithful rendering of its own classic and an icon of an entire genre. At the same time, it has managed to build a thoroughly modern, sophisticated timepiece that is at once haute horlogerie and a utilitarian tool, capable of surviving the bashing on a bucking dive boat, a five-knot current and 16 fathoms of depth over four days of arduous diving. When I returned home from Florida, I noticed that the famous Blancpain timing bezel was still set where I’d left it during our search, a grim reminder of an unfathomably frightening day on the water.