Submariner 5513 is the first Rolex watch equipped with this highly specialized technology. And they were used as prototypes when Rolex worked with COMEX to develop the final design of the gas relief valve. Instead, with the advent of the single Red Sea-Dweller, the new features of replica Rolex dive watches were the addition of a depth rating and the extra date complication so that divers living and working below the surface could track the time of day in addition to the time spent underwater. 
Seven of the 12 single Red Sea-Dweller models are not fitted with a helium release valve. The problem of trapped helium molecules forcing the crystal to “burst” during decompression only occurs at greater depths when divers live for long periods in a helium-saturated environment. In much shallower waters, these same problems do not exist. For example, the divers who participated in Tektite 1 did not use a helium drain valve on their watches because, due to the relatively shallow depth of the project, the gas mixture they used consisted only of nitrogen and oxygen.
This 2013 watch was sold by its original owner, who had a fascinating career as a diver in the underwater demolition team. Moreover, the original bezel was lost while diving to over 200 meters. It is also quite remarkable that it still has its original dial, considering I repaired it in 1993. All that is known about the 2012 example is that it was purchased by a Japanese collector in the 1980s and has not been worn since, being hidden away in a safe deposit box.
Each of these coveted 1665 Sea-Dweller watches gives us a general idea of its value, which in today’s market is probably much higher than these prices. Of course, the condition of the fake watch and the presence of all the original parts also play a major role in the price of the 1665 Mono Red. However, with examples exceeding $700,000 back in 2018, it is easy to see how it could easily fetch more than $1 million if it appeared at auction today.
Given its extremely limited production run and well-documented history of rigorous professional use, the Rolex Mono Red Sea-Dwyer watch is very rare and seldom appears at auction – let alone on the wrist of someone you might encounter daily. While only 12 known examples exist, Rolex has never confirmed details such as production numbers, so there is always a glimmer of hope that a 13th single Red Sea Defender could be the next “warehouse find” for someone very lucky.
