Most importantly, the X Fathoms has a mechanical depth gauge, shown in the central of the dial via a display with 0-90 markings in yellow and a short dedicated hand. As the display indicates, the depth gauge works from 0 to 90 meters. This function is rarely seen in mechanical watches - although Panerai, IWC and JLC are the three brands that have produced mechanical depth gauge wristwatches in the past. The biggest advantage of a mechanical depth gauge being built in to a timepiece, is that it eliminates the need for a dedicated depth gauge. Many divers wear both a depth gauge and professional dive watch.
The X Fathoms has some other important and unique diving features such as: a 5-minute counter for decompression stops shown via a retrograde at 10-11 o'clock on the dial, a separate indication from 0 to 15 meters that is marked on the outer part of the dial and indicated via a dedicated hand and water-resistance to 300 meters (which although not record breaking, is well above the ISO 6425 standard that requires a minimum of 100 meters, and way more than you'll ever need). It also features the prerequisite unidirectional rotating dive bezel (with the signature Fifty Fathoms style sapphire bezel) and helium decompression valve.
The case measures a massive 55.62 mm in diameter and is made of titanium that has been satin brushed. But don't worry about the size, as this watch is not as much about form as it is about function, its a diver for professionals. The case back has an amorphous metal membrane that is part of the mechanical depth gauge mechanism.
The movement is new, caliber 9981B, based on the Blancpain caliber 1315. It has three barrels which ensures a power reserve of 120 hours (5-days). The balance spring is made of silicon which is resistant to magnetic interference, requires very little maintenance and overall is more stable.
Even the strap is specially designed for this superlative timepiece. According to Blancpain it's, "The most complex injected rubber strap ever conceived gives the final finishing touch. It comprises 14 articulated parts to ensure a perfect fit on the wrist and allow water to seep in under the watch in order to come in contact with the membrane under all circumstances."
The Blancpain X Fathoms is a testament to advanced micro-engineering and clearly one of the most advanced dive watches on the market.