When diving, it is as important to know your depth as it is your time. For most divers nowadays, this means using a digital dive computer that puts all the data on your wrist. But for those who prefer to dive old school, or who subscribe to the “two is one, one is none” philosophy of having backups, using a dive watch and a separate depth gauge is required. Since the 1970s, watch companies have tried, with varying success, to incorporate depth gauges into their watches using everything from Bourdon tubes filled with oil, to pressure-sensitive membranes, to electronic pressure sensors. They have ranged from haute horlogerie (Jaeger-LeCoultre) to the downright cheap (Swatch Scuba). Swiss watch company, Oris, just introduced their own entry into this rather narrow but deep (pun intended) niche market with their Aquis Depth Gauge ($3,570).
Oris is well known for their dive watches and are favored for their handsome lines, reasonable pricing and rugged reliability. The Aquis Depth Gauge continues Oris’s familiar aesthetics — austere black dial, wide bezel (this time rendered with a ceramic insert) and 46mm steel case with narrow lugs that accommodate Oris’s high quality rubber strap or steel bracelet. The motor within is an ETA-based, Oris-modified, self-winding calibre 733. The real difference with this timepiece, of course, is the addition of the depth gauge, which is one of the more elegant integrations we’ve seen. The depth scale itself, marked in “meters below surface”, runs around the perimeter of the dial, with yellow numerals (yellow is visible to great depths) all the way to a nitrogen narcosis-inducing 100 meters.
Oris eschews current depth sensing technology, opting for a simpler and rather elegant means that brings to mind high school science class (Boyle’s Law anyone?). The Aquis is fitted with an extra-thick sapphire crystal, into which a channel has been milled around its perimeter. An orifice above the dial’s twelve o’clock marker allows water to enter this channel and compress the air within. As the diver descends, the increasing water pressure compresses the air in the channel further; the visual difference between water and compressed air provides the visual reference point on the depth scale. While we’re squeamish about extra holes in our watches, Oris assures us the crystal is well-sealed, and the watch is rated to a pressure of 50 bar, or the equivalent of 500 meters.
Compared to other depth gauge mechanical dive watches, the Oris Aquis holds its own but has one fatal, and unforgivable, flaw. For a depth gauge to be a truly useful backup instrument, it needs to display not only the diver’s current depth at any given moment, but also record his deepest reached depth. This is crucial for calculating no-decompression times and necessary surface intervals between dives. The Oris only has the capability of displaying the current depth due to its simplistic mechanism. This renders the depth gauge component of this watch more of a novelty than a true backup device. Still, its other features make it a capable backup bottom timer. And that’s more than most divers strap on these days.