The Sea-Dweller is absolutely not the most famous Rolex watch. It sits far behind the everlasting Datejust, the presidential Day-Date, and the James Bond-esque Submariner. However, its live has nothing to do with chance; it embodies what Rolex wishes to represent: producing durable replica watches for everyone, even those at the edges, including some of the saturation divers. 
The rolex Sea-Dweller was not Rolex’s first foray into niche markets. One might remember the True-Beat, with its jumping seconds, which was made for doctors, or the anti-magnetic Milgauss aimed at scientists. Both watches provided perfect technical features, but, as a result, they were stopped given the inherently small size of their respective target markets. It might then come as a surprise that the Sea-Dweller has been around for the past 50 years, concentrating on a narrow mission statement: go deeper than the Submariner on the wrists of saturation divers and survive anything.
The fake Rolex did not introduce the first dive watch when the Submariner was unveiled in 1954. No, Blancpain had debuted the Fifty Fathoms one year before, and replica Omega had already unveiled the Marine more than 20 years prior. There is no denying though that the Submariner became the best diver, with its aesthetic becoming the expected form factor for dive watches. Form following function, most of its design was born out of the need to comply with the ISO 6425 standard. Actually, its feat was to nail technical requirements and to achieve a pleasing look at the same time.
When the Sea-Dweller appeared in the late 1960s, the Submariner could already reach an impressive depth of 200 meters/660 feet; in no way was it an inadequate dive companion. So, the Sea-Dweller was not correcting flaws found on the Submariner in spirit but rather extending its underwater utility. Many divers in the Sealab expeditions had indeed noticed that one strange phenomenon kept on happening to their beloved Submariners – the crystal would often pop out in the decompression chamber after a dive. Obviously that’s no good.
It must be stressed that we are not talking about casual dives here, but hardcore underwater experiences, as the whole scientific purpose of Sealab was to study the effects of staying underwater for extended periods of time. This could only be achieved through saturation diving, and this is where the replica Rolex Submariner met a serious challenge. The pressure inside the watch would have to be let out through the weakest point of the watch during decompression, brutally expelling the plexiglass as that helium gas forced its way out.