With the watch collecting world still reeling from the shock of Rolex’s 50mm titanium Deepsea Challenge, your humble blogger continues his trek through the recent history of extreme dive watches. Today, we’re revisiting the gnarliest Blancpain Fifty Fathoms ever to hail from Les Brassus.

You only get one chance to make a first impression, and Blancpain made one for the ages with the 1953 Fifty Fathoms. It’s famous for setting the format of the modern dive watch – and doing so by beating the Rolex Submariner to market by a hot minute. 2011’s monstrous Fifty Fathoms “X Fathoms” wasn’t another attempt to define a genre, but it remains a formidable statement of capability and Blancpain’s ability to innovate in a segment it created.

To be precise, the X Fathoms was the third entry in a close chronology of luxury dive watches after the core reference 5015 of 2007 and the 48mm titanium reference 50015 of 2009. The latter year also brought 500 Fathoms GMT, and observers could have concluded that Blancpain’s honor had been satisfied. But as often happens with monsters of the deep, something massive lay just beneath the surface.

And at 55.65mm in diameter, the 2011 “X Fathoms” is massive. Primary, secondary, and tertiary roles of this machine are, respectively, “gauge,” “gauntlet,” and “gadget.” Only in the quaternary sense is this a “wristwatch.”

Start with the specs. Basic water resistance is 300 meters; the mechanical depth gauge is calibrated down to 90 meters. It is hyper-sensitive and capable of resolving increments of 30 centimeters. For decompression reference and post-dive documentation, a memory display highlights the maximum depth reached during a dive. Saturation divers can rest easy knowing that their $40,700 investment is protected from helium detonation by a gas escape valve.

And for – small-s – submariners surfacing from depths at which nitrogen enters the bloodstream, a five-minute countdown chronograph is included to time each decompression step during the surfacing process.

Let’s discuss the elephant seal in the room: size. No normal human being can wear a 55mm+ watch, and there aren’t enough people named “Schwarzenegger” and “Stallone” to fulfill even the limited production ambitions of Blancpain product planners. Something new was required.

In order to mate the hulking reference 5018 to a sub-Na’vi-sized arm, Blancpain created what it describes as the “world’s most complicated injected rubber strap ever conceived.” Composed of 14 primary components, the gauntlet-like band enabled an uneasy anschluß of wrist and watch. This isn’t the kind of timepiece that fits under a cuff, and even with its ergonomic gymnastics, the character of the “X” on a wrist is that of an aggressive power annexing a small neighboring state.

And you had better be happy with the occupation force, because no other bands are offered with the watch.

Beyond its wild price, size, and headline innovations, the X Fathoms boasts a solid roster of features familiar to any post-2007 Fifty Fathoms owner. The exotic caliber 9918B is based on the regular 1315, and key capabilities include automatic winding, a five-day power reserve, hacking seconds, a free-sprung balance, and three mainspring barrels. Blancpain’s much-loved sapphire bezel cap is retained to maintain the high-luxe aesthetic of the model 5015, and the bezel operates with unidirectional action.

Rolex remains the name of reference in the dive watch market. Now that the Rolex 126067 has hit the high seas, Rolex can claim for the first time in a while to be a leader in dive watch technology. But for those with big wrists, big budgets, and offbeat tastes to match, there’s a 55.65mm alternative from the Vallee de Joux. Just remember; it goes on your wrist, not your bicep.