Solarzilla: Reviewing the Citizen Promaster Eco-Drive Professional Diver 1000M

In a sea of retro-inspired dive watches launched during Baselworld 2017, Citizen stood out as one of the few brands that dared to launch something radically new. The Citizen Promaster Eco-Drive Professional Diver 1000m is the world’s first solar-powered watch capable of saturation diving – and the Japanese brand’s second 1,000-meter diver. We give it an in-depth review in this feature from WatchTime’s November-December 2017 issue.

Citizen Promaster Eco-Drive Professional Diver 1000M - bezel CU
The Promaster 1000m is ISO compliant and has been tested with JAMSTEC under operating conditions.

The Promaster Eco-Drive Professional Diver 1000m (Reference BN7020-09E) was one of three major Promaster additions introduced in Basel this year and, thanks to its uncompromising look and a 52.5-mm-large and 22.2- mm-thick titanium case, also the one that undoubtedly stood out the most. Perhaps more importantly, it’s one of the few watches that rightfully fall into the category of “extreme dive watches.” In other words, it’s a contemporary tool watch. Its primary function is to withstand even extremes of pressure and to safely measure elapsed time under water, even for saturation divers, and definitely not to fit under a French cuff dress shirt.

The new Promaster 1000m follows in the footsteps of Citizen’s first 1,000-meter diver, the 2002-introduced Promaster 1000m (Reference NH6931-06E and NH6930-09FB) with 48-mm titanium case, unofficially nicknamed the “Autozilla” (after the fictional Japanese giant monster). But instead of its predecessor’s removable bezel, the new model comes with an additional locking system that has a visual indication to show when the timing bezel is unlocked. (If the orange strip at 7 o’clock is visible, the 120-click ratcheting bezel can be rotated counterclockwise.) There is a similar indication to show if the crown, ergonomically placed at 4 o’clock, is open or safely screwed-in.

Citizen Promaster Eco-Drive Professional Diver 1000M - side
A giant from the deep: More than 52 mm in diameter and 22 mm in height, integrated strap adaptors and an automatic helium-release valve at 10 o’clock

In theory, a dive watch (or any diving instrument) can never be built to be too safe, so the additional ring to lock the bezel can definitely be described as a clever feature (and is actually very convenient to operate). In reality, a unidirectional bezel is already a safety feature, so it’s safe to say that the solution Citizen chose is another good example of the over-engineering that went into this watch. More importantly, the locking mechanism allowed Citizen to equip the bezel on top of it with just six large sawtooth-like elements, making it one of the easiest bezels to operate, even when wearing gloves. And speaking of gloves, Citizen is one of the few brands to offer a very practical solution for divers wearing a dry suit. The Pelican case-like box the watch is delivered in also contains an additional strap extension that’s long enough for most divers’ wrists and suits.

It’s also worth mentioning that for the numerals for the first 20 minutes on the bezel, Citizen has used a larger font (as well as for the 30 and 45 markings). This visual distinction can help a scuba diver keep better track of the first 20 minutes of a dive (which can act as an indicator for the point-of-no-return during an average dive with a standard 200-bar scuba tank). However, a professional saturation diver usually works at greater depths for long periods of time and is about as far away from recreational scuba diving as the Promaster 1000m is from being subtle on the wrist. A saturation diver lives in and operates from a pressurized environment for up to several weeks, and is decompressed to surface pressure only once, at the end of his tour. In other words, a date indicator suddenly becomes much more relevant to a saturation diver than a 60-minute diving bezel in combination with a prominent minutes hand. The same goes, again in theory, for the integrated helium-release valve.

Citizen Promaster Eco-Drive Professional Diver 1000M - helium valve
The case is made from Citizen’s “Super Titanium” alloy, a hardened (Duratect) material with increased scratch resistance. It is stated to be at least five times harder and approximately 40-percent lighter than stainless steel.

The rise of saturation diving in the 1960s (and hence the use of breathing-gas mixtures containing helium) was the reason that some watch brands started to equip standard dive watches with helium-release valves. Helium molecules inside a pressure chamber can work their way inside a watch. During decompression, the pressure inside the chamber can decrease more rapidly than the pressure inside the watch case. This can, in some cases, cause the watch crystal to pop off. The helium-release valve allows helium to escape from the case during decompression.

Instead of using a helium-release valve, other watch brands simply started to develop more robust watches, which led to the development of the first “extreme” dive watches, like the Omega Seamaster 600 PloProf and the Seiko 6159-7010 Professional Divers 600m – two different approaches to solve the same problem.

The Citizen Promaster Eco-Drive Professional Diver 1000m’s automatic helium-release valve is located at 10 o’clock, on the side of the brushed (and lighter than expected) titanium case, and is again an indication of how much over-engineering went into this watch. It wouldn’t come as a surprise if the same case were able to perform as well without the valve.

With a diameter of 52.5 mm, the case doesn’t have regular lugs or require spring bars. Instead, the strap is integrated directly into the case and secured by the caseback, which not only increases wearing comfort but also makes it virtually impossible to accidentally tear out the strap. However, the unique lug adapters used also make it almost impossible to get a third- party strap as a replacement. On the plus side, since the caseback is held in place by four screws, the engraved diving helmet is perfectly aligned. And yes, diving using a traditional diving helmet would be the third category of diving mentioned in this article, and also the one least likely to require a dive watch.

Citizen Promaster Eco-Drive Professional Diver 1000M - caseback
The engraved diving helmet on the caseback is perfectly aligned.

Speaking of requirements, Citizen’s use of an Eco-Drive movement for the Promaster 1000m requires a natural or artificial light source to charge the solar cells located just under the dial. And those immediately thinking about a formal objection can relax; the so-called “aphotic” zone (Greek for “without light”) of the ocean does indeed begin between depths of roughly 200 meters (660 feet) to 1,000 meters (3,300 feet). But divers seldom find themselves below 300 meters by choice, and secondly, there is still bioluminescence after that (but please don’t grab that poor vampire squid to charge your watch). Finally, if fully charged, Citizen’s Caliber 210 is supposed to run for about 1.5 years. In comparison, the longest time spent by a human being living in an underwater habitat was 73 days, 2 hours and 34 minutes at 7.31 meters (24 feet).

Additionally, Citizen’s Caliber J210 powering the Promaster 1000m offers an accuracy of +/-15 seconds per month, and it is estimated that the brand’s Eco-Drive system has helped reduce the disposal of millions of batteries since its introduction in 1995. Still, fans of mechanical watches probably would prefer the Caliber 8203 as an additional (and equally environ- mental-friendly) mechanical option.

The comparatively small dial of the Promaster 1000m sits under a slightly domed sapphire crystal. Citizen went for two rather large hands for its latest diver (the minutes hand in bright orange to better support its dominant role to indicate the elapsed dive time), a date window, large indexes and a power-reserve indicator. Despite its rather busy layout, the watch is actually easy to read, especially under water and in the dark. The luminous material used for the bezel, dial and hands is stated to offer “more than twice the afterglow brightness than a conventional material even after five hours,” according to Citizen.

Citizen Promaster Eco-Drive Professional Diver 1000M - lume
Large areas of Super-LumiNova on the hands and indices glow brightly in the dark.

The Promaster 1000m is ISO 6425 compliant and has been tested “for 15 days in a pressurized chamber that contains helium and oxygen or even 100-percent helium gas” and then reverted “back to atmospheric pressure within three minutes after high-speed decompression.” Citizen also partnered with the Japan Agency for Marine-Earth Science and Technology (JAM- STEC) to test the Promaster 1000m under operating conditions.

In summary, a dive watch like the Promaster 1000m is about as professional as possible, and criticizing it for being or looking too extreme (or vice-versa, for being unqualified as a desk diver) would be as pointless as trying to hide it under a shirt. It’s undoubtedly large but surprisingly comfortable to wear, refreshingly over-engineered, offers a unique design, and is pretty much up to any task related to diving.

The Promaster 1000m was most likely the most “serious” dive watch introduced in 2017, and given its equally serious price tag of $2,300, there is probably only one thing we could wish for: a second version for Baselworld 2018, powered by one of the brand’s well-known mechanical movements.

Manufacturer: Citizen Holdings Co., Ltd., 6-1— 12, Tanashi-cho, Nishi-Tokyo-shi, Tokyo 188-8511, Japan
Reference number: BN7020-09E
Functions: Hours, minutes, seconds, date, power-reserve indicator
Movement: Eco-Drive Caliber J210, +/-15 seconds per month, 1.5-year power-reserve when fully charged
Case: Super Titanium (Duratect, DLC), nonreflective sapphire crystal, water resistant to 1000 m
Strap and clasp: Black polyurethane strap with buckle
Dimensions: Diameter = 52.5 mm, height = 22.2 mm
Price: $2,300

Citizen Promaster Eco-Drive Professional Diver 1000M - soldier
The design of the bezel is inspired by the shape of a shell of a conch and is extremely easy to operate, once the bezel locking ring is set to “Free.” The orange strip at 7 o’clock indicates that the bezel can be rotated.
No Responses to “Solarzilla: Reviewing the Citizen Promaster Eco-Drive Professional Diver 1000M”

Show all responses
  1. Edward Rousseau

    What are the differences in the BN7020-17E and the BN7020-09E. I own a BN7020-17E

  2. John Shortland

    I dearly want. to purchase this solor 1000 meters divers watch it’s a life time investment to me

  3. Robotaz

    There is a company now making adapters for other straps and bracelets. You can find them online by looking for “citizen adapters”. I owned this watch before the adapters came out and now that they are available, I plan on buying one, again. It’s a very, very good watch for those doubting it. I’ve owned countless divers from most brands and this is by far the most purpose-oriented diver I’ve owned. But beware, it will not fit under any sleeve. It’s for diving or wearing with a t-shirt.

  4. JJ Stives

    The best thing about Citizen and its fine dive watches is that they not only work perfectly, but they offer reasonably priced repairs and tune-ups with great service. I cannot say this for other watch makers, no matter what the price. Like Sinn, the degree of overkill (1,000 meters), is a good conversation topic, but even for sat dives, it is of little use. As we say, “if you go that deep, you ain’t coming back.” I have several Citizens and they all perform as perhaps Rolex and Breitling wish theirs might. Thanks for the review,

    JJStives, FAA Commercial Pilot and Certified Commercial Diver, Fort Pierce, FL

  5. Neil Mcbride

    I recently purchased this watch and its everthing i thought it would be,but one thing worries me,the divers helmet on the case back does not alighn with the watch strap,is this normal?

  6. Neil Mcbride

    What would you look for if you thought the one you bought was a fake!


    This one keeps tempting me but not being able to put what bracelet you want on it is annoying

    • andrew friedman

      the more mundane 300m water resistant ‘ecozilla’ watch has a similar feature for attaching the strap – and is capable of fitting aftermarket lugs that can secure a more traditional band or strap. google citizilla or suppa parts. Not sure either after-market company’s lugs can fit this larger watch, but it might be worth asking. I have the aftermarket lugs on BJ8050 dive watch, and they are a very functional and great-looking alternative, if you don’t want the rubber dive straps.

Leave a Reply