What does Bulova have in common with Jaeger-LeCoultre, Longines, Blancpain, Universal Geneve, and Zenith? They all sold the same damned watch.

Super Compressor diving watches are a category unto themselves, and the best Swiss brands sold versions of the distinctive dual crown watches that have been one of the most popular types of dive watches for years.

The Super Compressor name refers to the innovative case design, which utilizes a "compressor" system that’s designed to become more watertight the deeper that the watch went under water. As the atmospheric pressure increases along with depth, the case back in compressed, pushing on the gaskets and creating a tighter seal.

The compressor case wasn’t any better at preventing water intrusion than a screw-down crown (in fact, it was probably worse), but due to their good looks, compressor cases proved to be popular during the 1960s. Eager to get into the burgeoning dive watch market, many of the best Swiss brands turned to EPSA (Ervin Piquerez, S.A.), the leading manufacturer of compressor cases at the time, for cases to build their divers around.

This particular example is branded by Bulova, and features a classic 36mm ESPA case with dual crowns and an internal rotating dive bezel. It is perhaps the internal bezel that has become the most endearing feature of Super Compressors to collectors today, and the idea behind them is that they’re less prone to accidental rotation that an external bezel. They worked out great for warm water divers, but anyone with gloved hands would have been out of luck (but at least stylish!).

The example is in excellent condition and looks every bit the part of a vintage dive watch. It’s sporty yet comfortably sized, and conveniently houses an automatic Swiss movement. Nice examples of Super Compressors are drying up, so now’s the time to dive in!

For more information on the history of compressor-cased diving watches, click over to Scubawatch.org, .