The SAGA:
What’s saturation diving you ask? It’s a form of deep sea diving that enables divers to go deeper, stay deeper for longer, and all with less risk of decompression sickness (the bends). Divers board a ship and head for their home for the next few weeks: a hyperbaric chamber the size of a New York City bedroom. As the chamber is pressurized to the depth the divers will be working at, all of the surface air will be replaced with a helium-dominant mix of gasses, with very little oxygen present.
At depth, the human body is quite permeable and gasses mix into solution in its tissues. As you proceed to surface pressure, those gasses now want to come out of solution. It’s important that this happens slowly. Much in the same way one opens a bottle of seltzer. If you open it too quickly, you’ll have a mess on your hands.
The watch on your wrist is also subject to the same gasses and pressures during diving. While a Rolex Oyster Case keeps water out, at depth it is permeable to the helium atoms. While living in the deep, those atoms are small enough to pass right through the steel case of your watch and populate the void inside. When returning to surface pressure, the permeability of the case fades away, yet the gas is still trapped inside the watch. Many divers reported the crystals of their watches popping off like champagne corks. What to do?
Enter the Helium Escape Valve. That little button-lookin-thing on the side of the case is the hallmark of the Sea-Dweller watch. When ascending to surface pressure, this one way valve lets the helium out, while keeping water from coming in. With this innovation, neither you, nor your watch will get “the bends.”
Tech Specs:
Year of manufacture: 1978
Serial Number: 569XXXX
Dial: Excellent Mk II “rail dial” with warm, sandy lume plots and matching hands. the 12 o’clock marker has aged slightly lighter than the others.
Case: Wonderfully sharp case with very prominent original bevels.
Bracelet: period-correct 93150 with full links and 585 end links.
Movement: Rolex caliber 1575
Accessories: Inner Box, outer box, booklets, punched papers, serialized hang tag, extra link, and anchor.
Watch is currently running at COSC spec