Boyle’s Law states that as the volume of a gas decreases, its pressure increases. PV = k. Pretty simple stuff, even to my nitrogen-addled brain as I coasted over the edge of the reef and checked my depth, which read a shade over 25 meters. Frankly, I hated science in school, but if the experiments we did back then had involved scuba diving in the Caribbean with a Swiss watch on my wrist, I might have opted to major in Physics instead of English Literature. The watch I was wearing on this dive, the ORIS Aquis Depth Gauge, aside from its chunky-handsome looks and colorful dial, is a perfect example of Boyle’s Law at work, a principle I was testing on every dive during a recent week in Bonaire.
ORIS has always been a favorite of real dive watch fans, thanks to the classic diver looks, solid build quality, and affordable prices. But last year, ORIS debuted the Aquis Depth Gauge, which ratchets up the usefulness of the watch for actual diving, thanks to an integrated mechanical depth gauge. As we discussed a few weeks ago, depth gauge watches typically make use of some sort of pressure membrane or Bourdon tube mechanism and mechanical needle to indicate depth, but the Aquis Depth Gauge uses water itself as the gauge. Defying convention, the watch has an orifice in the sapphire crystal that lets water enter a channel around its circumference. As the water pressure increases at depth, the air inside the channel gets compressed and the line where air and water meet shows the depth against a scale printed on the dial below. It is a very elegant solution with no moving parts. But how well does it work? I wanted to find out.