The topic of water resistance can feel messy at times, mostly because brands provide conflicting advice for the same depth rating. When heading underwater, using an actual dive watch is more important than relying on a depth rating alone. As recreational diving finds its limit at around 40 meters, three key attributes to look for are robustness, underwater legibility, along with easy bezel and strap operation.
Military needs and the rise of SCUBA diving encouraged brands such as Rolex or Blancpain to develop the first “modern” diving watches. As commercial saturation diving expanded in the 1960s and 1970s, professional divers began working at much greater depth in a helium-rich environment. This shift led watch brands to rethink their approach and produce a new generation of highly specialised diving watches.
Jenny, a watch case manufacturer, made history by producing the first watch rated to 1000 meters. At the same time, the French diving company COMEX was testing prototypes from both Rolex and Omega, which would later evolve into the Rolex Sea-Dweller and Omega Ploprof. Both watches were rated to 600m, and relied either on a helium valve or a monobloc case. These two “super” divers were used almost exclusively by industry professionals.
Even though these watches already exceeded the depths where saturation divers actually work, the next big step arrived in 1978, when Seiko released the first quartz watch built for saturation diving. In the 1990s, diving computers became mainstream, and the diving watch was pretty much relegated to enthusiast territory only.
Strangely enough, luxury brands kept racing to the bottom of the Mariana trench, by pushing for more and more extreme depth ratings. Wearing an “ultra deep watch” often leans closer to strapping on an essential piece of diving gear than a conventional watch. This uselessness is precisely where the appeal lies, and these exceptional pieces of engineering really form a category of their own. With that in mind, let’s have a closer look at five models truly matching this description.
Hervé's Top 5 'Ultra Deep' Dive Watches
Seiko “Emperor” Tuna automatic 1000m (about 10 football fields)
The Seiko Tuna remains one of the most distinctive watches ever released by the brand. The ceramic shroud improves shock resistance, and the patented L-shaped gasket completely eliminates the use of a helium valve. Inside the titanium monobloc case sits the 8L35 movement, which shares its architecture with the Grand Seiko 9S55. While the “Emperor” Tuna is not a small watch, measuring 48.2mm per 17.4mm, its lugless design makes it more wearable than the dimensions suggest.
One might wonder why a watch “only” rated to 1000m earned a spot on this list, but Seiko is known for being conservative with its official technical specifications. In 2014, Seiko attached four randomly selected Tuna to a JAMSTEC deep sea submersible. The quartz version survived down to 3284 meters and the automatic reached an astonishing 4299 meters before stopping. Since this model appears to have been discontinued, now could be a good time to hunt one down.
Oris Aquis Pro 4000m (roughly the height of Mount Fuji, but upside down)
Let’s just say it : the Oris Aquis Pro is a beast. Its diameter is large at 50mm, but the real surprise is its thickness, coming in at 23.4mm. To picture it, imagine stacking two Tudor Black Bay on top of each other.
The “Rotation Safety System” bezel technology is a key feature of this watch. To avoid accidental manipulation, the bezel can only be adjusted when the rubber grip is lifted up, before being locked back into place with a single push. The clasp also offers a quick and practical extension to fit over a wetsuit.
Inside the multi-piece titanium case sits Oris’s Calibre 400, known for its five days of power reserve, great accuracy and ten years service interval. The helium valve is positioned at nine o’clock, and the watch is backed by a ten year warranty. The Aquis Pro stands out as a serious pick in this group.
Sinn U50 Hydro SDR 5000m (about the height of 50 Statue of Liberty)
Some may question listing the Sinn Hydro here, since it takes a different approach with its oil filled conception. The oil inside the case removes the issue of compression, and allows the watch to achieve a remarkable depth rating. It also brings undeniable benefits, like slim dimensions and a glare free underwater legibility.
The U50 Hydro measures 41mm per 11.8mm, which is surprisingly wearable for a 5000 meter watch. The case is built from German submarine steel hardened by Sinn’s Tegiment surface treatment. Since the case is full of oil, the watch relies on a Ronda 715 Li quartz movement which delivers a long battery life and performs well in even extreme temperatures. For collectors open to quartz, the U50 Hydro reconciles extreme depth rating with daily wearability.
Omega Seamaster Planet Ocean Ultra Deep 6000m (or 7 Burj Khalifa)
Omega developed the Ultra Deep from a 28 millimeter thick prototype that reached the bottom of the Mariana Trench at 10,928 meters. The production model is more restrained at 45.5 per 18,1mm, which is relatively wearable for a watch rated to 6000 meters. Unlike many of its competitors, it also looks more like a luxury sports watch than a piece of diving equipment, which is a big plus for everyday wear.
Omega offers the Ultra Deep in O-Megasteel or titanium. Beyond the weight difference, the designs differ quite a bit. The steel model keeps traditional lugs that work with a bracelet or rubber strap. The titanium one has “manta ray” opened lugs that work only with fabric straps and give the watch a more stealthy look. A revised crown and gasket setup prevents helium from entering, which removes the need for a helium valve
The Ultra Deep uses Omega’s 8912 caliber, which includes co-axial technology and delivers 60 hours of power reserve. Being METAS certified, the watch can handle magnetic fields up to 15,000 gauss and is accurate from 0 to +5 seconds a day. The Omega Ultra Deep 6000m has succeeded in marrying luxury watchmaking with serious engineering.
Rolex Deepsea Challenge 11000m (about as high as a long haul passenger jet)
In 2022, Rolex set a new milestone with the Deepsea Challenge, a watch rated at 11000 meters and currently the deepest production model currently on the market. It is also the brand’s first watch made in RLX grade five titanium.
A watch rated to more than 1000 bars cannot be compact. The Deepsea Challenge measures 50 by 23mm and still weighs 250 grams despite being made of titanium. The sapphire glass alone is nearly 10mm thick. Rolex tests each watch to 25 percent beyond its depth rating, reaching the equivalent of 13750 meters.
The Deepsea Challenge looks like an oversized Sea Dweller, and features Rolex technologies like the Ring Lock design, the Triplock crown and the Oysterlock clasp. Inside the watch beats the 3230 movement, which offers about 70 hours of power reserve and an impressive accuracy of -2/+2 seconds a day.
Even with its brushed titanium finish, the watch is impossible to miss. You can look at the Deepsea Challenge in two ways. As an everyday watch, it is close to unwearable. As a piece of Rolex research brought to the public, it becomes a fascinating object.
