Barth tells of how he and his fellow crew members in an interview conducted by Jason Heaton back several years ago, while undergoing decompression in a decompression chamber, would hear a quick “pop” sometimes only to find that the crystal of someone’s fake watch – Submariners, Blancpain’s, and Tudors, mostly – had come off. The basic problem was the helium in the breathing gasses used in SEALAB. Helium forms very small molecules, which can over time penetrate the seals of a dive watch and build up in the case. Divers would spend a few days in a decompression chamber, where air pressure would gradually be lowered from that at working depth, to air pressure at sea level. The helium would not be able to leak back out of the watch case quickly enough and the result was increasingly greater pressure inside the watch case – often, enough to pop the crystal off. It was the SEALAB missions that first called for a helium escape valve, which was introduced within the fake Rolex range on the Sea-Dweller and remains a staple of this model to this day.  
There are a few early Sea-Dwellers that have only one line of red text on the dial. These “Single Red” Sea-Dwellers are exceedingly rare, feature a depth range of 500m instead of 600m, and often times do not have a helium escape valve. These are prototypes and generally fetch hundreds of thousands of dollars at auction, such as this one did in 2013.
The Rolex Sea-Dweller replica watch was introduced in 1967 as Rolex’s biggest, badest, most capable dive watch. It was water-resistant up to 610 meters and featured two lines of red text reading “Sea-Dweller / Submariner 2000”. The crown was a Trip-Lock; the watch featured a date (useful to saturation divers who could spend days in a decompression chamber) and it was the first time a Rolex diver would feature the complication, predating the 1680 Rolex Submariner ever so briefly.
The bracelet had an extension clasp that allowed the owner to quickly open up the bracelet to allow it to fit on the outside of a diving suit. What’s more, the crystal was domed and cyclops-less. This is how the replica Sea-Dweller watch was born and how it remained for some time and over the years we would see continual improvements to water-resistant engineering in Rolex’s most professional line. Of course, we know it, actually after the Rolex replica killed the Sea-Dweller.

Now we are enjoying the summer and I am wondering if you know what that means: new summer swag. We have an amazing lineup of hot-weather-friendly watches for you this week including a ton of steel dive replica watches and many other yellow gold numbers for those hot summer nights.
There is a Rolex replica which is one of the most sought-after vintage Rolex Submariners. With its perfect proportions and dateless dial, this watch is the ultimate dive watch. The example we have here dates to 1977 and features a “Pre-Comex” dial, which you can identify by the distinctive Coronet crown and those oversized tritium lume plots. We prefer this one for its creme brulee patina and its rough-and-tough look. What’s more perfect than a dive watch for summer?  
The vintage Rolex Daytona seems ubiquitous in auction catalogs these days, but finding a nice yellow gold one always proves a challenge. Among all, this replica watch is one of the most actively pursued, especially with a black dial. Obviously, the appeal is easy to obtain, and the black bezel and back dial contrasting nicely with the yellow gold case. And the screw-down pushers give even more presence to the 37mm case, in addition to the increased water resistance (although we really don’t recommend exposing any vintage Daytona to water nowadays). 
The example here shows a sigma dial, with the small symbols placed at the bottom of the dial around the “T-Swiss-T” line. This denomination is consistent with the 1977 production date implied by the serial number engraved on the case. The tritium lume on the handset has taken on a nice patina, but you won’t fail to notice a couple of missing lume plots on the dial. The most important is, this fake Rolex Submariner kept its original pushers and its case was not excessively polished, as evidenced by the curves of the lugs. And the yellow gold rivet bracelet is just the sweet finishing touch, especially since its links keep tightly attached (loose stretch being common on those vintage bracelets).