With this post I would like to introduce a new series on Lug2Lug – Throwback reviews. In this series I’m going to review watches that I used to own, during one point or another, before I started the Lug2Lug blog. I think it might be interesting experiment to stop for a moment and look back at watches that I used to own. This broader perspective could allow me to be more objective and not driven with emotions like after unboxing a brand new watch. The first hero of this brand new review series is going to be a true dive classic by Seiko: Marinemaster 300 SBDX001 or MM300 for short.

Seiko MM300 SBDX001 is referred to as a Japanese Submariner, no wonder both watches are often compared to each other. Chriscentro did it as well on his guest entry on Lug2Lug, you can see it here. The Marinemaster concept is not a new one. It was first introduced in 1967 in a form of Seiko 6215-7000 and it was replaced two years later by 6159-7001. These watches become real classics and highly collectible pieces. In early 2000’s, Seiko decided to bring back this original design and released Seiko SBDX001. You could say that Seiko made a reissue before it was cool 🙂 The watch retained the overall look of its predecessors, including the monoblock case.

Seiko MM300 SBDX001 on nato strap

Over the years, Seiko released various Limited Edition models and finally replaced the SBDX001 with the latest SBDX017 a few years ago. This ultimate MM300 form is basically the same watch as SBDX001 but it has been treated with DiaShield coating to increase the scratch resistance. This subtle evolution is partially a reason why MM300 is called a Japanese Submariner because, similarly to the famous Rolex watch, it hasn’t changed much over the years, only improved with the latest industry achievements.

That’s on top of already impressive specs: monoblock case, 300 meters of water resistance, and 8L35 automatic movement. That was a reason why Seiko MM300 become one of the most recognizable and respected watches in Seiko portfolio.

Case, bezel

One of the most unique things about MM300 is its monoblock case. Instead of having a regular screwdown caseback, Seiko MM300 has a monoblock construction. There is no caseback at all, and the only way to get inside the watch is through the front glass and dial. While this solution has its obvious advantages such as highly improved water resistance and the fact of being impenetrable for He gas, it has some downsides too. The access to the movement is hindered because you have to remove bezel, unscrew a retaining ring, which keeps a double domed hardlex crystal in place, and remove the gasket, hands, and the dial. This also means that the number of watchmakers skilled enough to service this timepiece is rather limited. From what I’ve heard, even official Seiko service centers in Europe do not service these watches on site but rather send them back to Japan. The increases both waiting time as well as the costs.

Seiko MM300 SBDX001
Seiko MM300 SBDX001
Seiko MM300 SBDX001

Nevertheless, this 44 mm case is a little piece of art. It is beautifully finished with a mix of brushed and polished surfaces, which complement one another. Even though it’s 44 mm case, it doesn’t wear large at all. It’s because the base of the case is actually significantly smaller, and the case gets to full 44 mm in the middle of its height, if this sentence makes any sense. The lug to lug distance is also not overwhelming at 50 mm, which makes it a great everyday watch. While on the wrist, I would say it wears similarly to a Seiko SKX007 or a Seiko Monster. The only significant difference is in height, Seiko SBDX001 has an impressive 15 mm height. I’ve heard that’s the main reason why people dislike this otherwise fantastic watch. It’s hard to argue with that if you plan to wear this was in office with a dress shirt, it simply won’t fit under your cuff. On the other hand, keep in mind that’s a tool watch after all and it’s meant to be worn in a completely different environment.

At 4 o’clock there is screw-down crown partially integrated in the case. It operates smoothly and doesn’t pose any issues from what I remember. However, a slight letdown is that the crown is unsigned, there is nothing on it just like on an entry level watch. Why? Seiko logic is sometimes tough to follow.

Seiko MM300 SBDX001 Macro

And now to the bezel. Oh, I’ve heard stories about this. They even made me think if I should really get this watch in the first place. Many people reported that it gets really stiff and hard to turn after some time. Luckily, it wasn’t a case in my unit. If anything, it was too loose and there was some back play involved. I think it’s unacceptable on a watch with MSRP of ~$2000. And that’s not all, the bezel insert is not that great either. I’m not really sure what was the material used for its production, I believe it was an aluminum insert covered with a layer of transparent lacquer to give it a glossy premium look. And while it looks great on a brand new piece, it’s highly susceptible to scratches. You could literally scratch it with a button of your shirt. No a great feature to have on your high end watch.

Dial, hands, lume

I love the dial and it’s layout of MM300. Simple as that. The slightly grainy black dial is close to being perfect. The indices are big and bold, they have a chrome border around them and they are filled in with Seiko lume. Reportedly, the lume is applied manually by Seiko watchmakers, which adds more flavor to the watch. At 3 o’clock there is date window, with a printed boarder. The interesting fact about the date disc, is the fact that it looks like brushed metal, which gives it that industrial tool look.

Seiko MM300 SBDX001 macro
Seiko MM300 SBDX001 macro

There is quite a lot of printing going on the dial as well, including the logo. Personally, that’s the only thing I dislike about this watch. At this price point, an applied metal logo would be a much better choice. Don’t get me wrong, the printing is fine and it’s well executed. It’s just my personal preference.

On of the most beautiful things about this watch is its handset. The hour and minute hands are just marvelous. They have brushed finishing with a fairly large grain, which is visible with an naked eye. This clashes with polished beveled edges creating this eye-pleasuring three dimensional composition. These are by far the most beautiful hands I have ever seen on a dive watch in any price range. And I don’t feel like I’m exaggerating here.

Seiko MM300 SBDX001 lume

The front of the watch is protected by a double domed Hardlex crystal. It’s a shame that at this price point Seiko did not got with Sapphire instead. Although Hardlex looks fine, it gets scratched quite easily. It got some minor marks on the crystal and I don’t even recall bumping into anything with my watch. It’s really a high time for Seiko to up their crystal game in higher end timepieces.

Movement

Seiko MM300 SBDX001, as well as all the other modern variations of this watch, is powered by a 8L35 automatic movement. It’s an really interesting movement not only because of its specification, which is also quite impressive to be honest. It features 26 jewels, 50 hours of power reserve, and 28 800 BPH. It’s factory accuracy should be within -10 to +15 seconds per day but it’s usually much more accurate. Mine run at about -5 seconds per day. Of course, it has such a basic functionality like hacking and hand winding as well. But the reason why the 8L35 is really interesting, is the fact that’s an undecorated version of 9S55 movement, which is used in much more expensive watches from Grand Seiko line.

Seiko MM300 SBDX001 Lume
Seiko MM300 SBDX001 wristshot
Seiko MM300 SBDX001

There is one more woth mentioning thing about this movement. At the end of SBDX001’s span life and before the release of it’s successor SBDX017  Seiko changed their movement manufacturing process. They introduced a new process of creating movement parts, which is 2-5 greater than any other machining method. They call it MEMS:

MEMS is an abbreviation for micro-electro-mechanical systems—a state-of-the-art processing technology used to manufacture semiconductors and other high-precision components. MEMS differs from the old metal processing methods of pressing, cutting, and polishing. Instead, shapes are made using photolithography (a process similar to developing photos using light-sensitive chemicals), on top of which a thick plating is deposited using electroforming technology. This processing method allows the manufacturing of complex shapes with greater accuracy than cutting, and also produces smoothly finished surfaces. In addition, hard materials can be used for parts while slightly adjusting the shape to keep the weight down, thereby greatly improving the accuracy and durability of the watch parts.

Bracelet and wearability

Seiko MM300 SBDX001 comes on a stainless steel bracelet with a ratcheting diving extension clasp. I have really mixed feelings about this bracelet. First of all, it does look great and balances this top heavy watch perfectly. It’s by far the best possible combination to wear this watch. However, there are some things do dislike about this bracelet as well. I don’t know how to put it other words but it’s just low quality bracelet for the price you pay. Before I bought MM300, I have had another Seiko classic, blue SUMO SBDC003, which had quite a decent bracelet and cost approximately 1/4th of the SBDX001. I was shocked when I got my MM300 and found out that it’s bracelet was not better, if not worse, than the one on SBDC003. Don’t get me wrong, it’s not terrible or anything. It’s just disappointing. It’s noisy and it makes this ugly squeaky sound unless you get a perfect snugly fit.  The ratcheting clasp is also a mixed bag. It’s great when it’s hot outside and you can expand the bracelet on the fly. But on the other hand, the claps is bulky and gets scratched easily while desk diving because of that.

Seiko MM300 SBDX001 wristshot

In the box with the watch there is also a rubber strap supplied by Seiko. You probably already seen it, as it is the famous waffle-pattern diving strap, which was copied by different manufacturers on Ebay. It’s goes quite well with the watch; although, it’s not very comfortable because of its stiffness. That’s why you should rather check after market options. As usual with dive watches, Isofrane style straps or nato straps are probably your best bet. However, in case of MM300 there is also one more thing you might want to look at. And that’s Crafterblue rubber strap. It fits the case perfectly and you can use your MM300 clasp to make it look like it was made that way by Seiko itself. On top of that, Crafterblue strap is also extremely comfortable. You can check out my review of their strap here.

Seiko MM300 SBDX001
Seiko MM300 SBDX001 wristshot
Seiko MM300 SBDX001

Seiko MM300 is quite a bulky watch. The head is heavy and it’s important to balance it well on the wrist. The stock bracelet does the job right; although, it’s not the highest quality bracelet out there. Nevertheless, it was the best combo for me, which was really comfortable on my 7,5″ wrist. The watch sits a little tall on the wrist which is something you either love or hate. I do like high watches so that didn’t bother me at all.

Conclusions

One of the most common question I get about MM300 is “why did you sell it?” The true answer is that I needed money to fund another grail on my list, Omega Planet Ocean 8500. Do I regret it? No… and yes. I don’t regret it because I managed to catch my grail obviously. And at the same time I regret it because I really liked the watch, and I remember I still do whenever see some pics on the web. Hopefully, I’ll be able to correct my mistake and get Seiko MM300 back at some point as it is a true classic that every dive watch enthusiast should have in their collection.

The first Throwback review is almost over. I think it’s a great way to distance myself from the watch that I no longer have in my collection to objectively see what it really is. It’s especially true to such a classic timepiece as Seiko MarineMaster 300 SBDX001. It carries a great deal of Seiko history and dive watches in general. It’s one of the most recognizable Seiko timepieces along with SKX007, Monster, or Tuna. However, I think that for someone who doesn’t really care that much about the history and is not a Seiko fan, MM300 could be a disappointing  investment. Of course, you probably won’t find a brand new SBDX001 anyway, but there is also the latest version, SBDX017. Nevertheless, at $2000+ price range there are plenty of interesting dive watches which could give MM300 a hard time. However, if you can get an used one at a discounted price, I encourage you to go for it. Even if you don’t fall in love with it, you can still easily flip it and don’t lose any money in the process.

PROS:

+ MM300 is a real Seiko classic and it will be for many years to come

+ The case is a little work of art

+ Amazing dial design and probably one of the most beautiful handset on a dive watch ever

CONS: 

– No sapphire crystal

– Bracelet is not on par with the watch in terms of quality

– Might be hard to service it locally

Model Seiko SBDX001
Diameter 44 mm
Thickness 15 mm
Lug to Lug 50 mm
Lug width 20 mm
Crystal Double domed Hardlex
Movement 8L35 automatic, 50 hours of power reserve
Water resistance 300 m ISO certified
Price discontinued, replaced by SBDX017 ~$2400

 

Image gallery

Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Macro Seiko MM300 SBDX001 Macro
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Lume Seiko MM300 SBDX001 Lume
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 wristshot Seiko MM300 SBDX001 wristshot
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 macro Seiko MM300 SBDX001 macro
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 wristshot Seiko MM300 SBDX001 wristshot
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 on nato strap Seiko MM300 SBDX001 on nato strap
Seiko MM300 SBDX001 on nato strap Seiko MM300 SBDX001 on nato strap
Seiko MM300 SBDX001 lume Seiko MM300 SBDX001 lume
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 wristshot Seiko MM300 SBDX001 wristshot
Seiko MM300 SBDX001 lumeshot Seiko MM300 SBDX001 lumeshot
Seiko MM300 SBDX001 wristshot Seiko MM300 SBDX001 wristshot
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 on nato strap Seiko MM300 SBDX001 on nato strap
Seiko MM300 SBDX001 wristshot Seiko MM300 SBDX001 wristshot
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
Seiko MM300 SBDX001 Seiko MM300 SBDX001
7.5 Classic

The first Throwback review is almost over. I think it's a great way to distance myself from the watch that I no longer have in my collection to objectively see what it really is. It's especially true to such a classic timepiece as Seiko MarineMaster 300 SBDX001. It carries a great deal of Seiko history and dive watches in general. It's one of the most recognizable Seiko timepieces along with SKX007, Monster, or Tuna. However, I think that for someone who doesn't really care that much about the history and is not a Seiko fan, MM300 could be a disappointing investment. Of course, you probably won't find a brand new SBDX001 anyway, but there is also the latest version, SBDX017. Nevertheless, at $2000+ price range there are plenty of interesting dive watches which could give MM300 a hard time. However, if you can get an used one at a discounted price, I encourage you to go for it. Even if you don't fall in love with it, you can still easily flip it and don't lose any money in the process.

  • Design 9
  • Watch quality 8
  • Bracelet quality 6
  • Value 7
  • User Ratings (13 Votes) 5.7
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About Author

Watch enthusiast who loves to take photos of his watches, blogger, and founder of Lug2Lug.

  • Gorga Naibaho

    For some reason I never warmed up to the MM300 despite it being the superior watch to my Orient Saturation Diver, which is also a 300m diver. Perhaps I’m biased because I was feeling cheap when I was interested in both, and decided to get the OS300 first because it was almost exactly half the price of the MM300 – something which drove many people to say that the Sumo is a more fitting rival for the OS300. Other than the above, because the OS300 is priced like a 300m Tuna but is an automatic, and also because the OS300 looks more toolish and less refined than the MM300, I tend to not be afraid of beating it and that made me appreciate it more in the end.

    • OS300 is definitely more robust, tool-like watch than MM300. I had a chance to briefly own OS300 and it felt like a tank compared to MM300. It’s also bigger and heavier, it won’t fit everyone’s wrist. Out of this trio: OS300, MM300, 300M Tuna only Tuna is left in my personal collection and I don’t intend letting it go 🙂

      https://uploads.disquscdn.com/images/fc7567516adc9b83a0a2b2f0b407edff078b55c13e1dd7d06c52b73b4002d6c2.jpg

      • Gorga Naibaho

        Great photo. I think one day I will also own all 3. This incredible trio can easily be anyone’s 3-watch-only collection to cover any need, from suited up meetings to holidays and even doing rough work. Well, that’s if you don’t bring G-Shocks – which I’m also fond of – into the equation.

  • dennis

    I could name a dozen watches costing half the price, all Swiss, that serve as a much
    better dive watch. The case reminds me of some vintage Omega’s i had, not many
    watch makers would work on them, hence, comes the screw down case back. Seiko
    was not thinking when producing this piece, not worth the money.

    • Fair enough. However, MM300 is not a watch for everyone. As a Seiko fan, I’m inclined to spend such amount for technically inferior watch just to have a chance to own a piece of Seiko history. It’s kind of similar to Rolex Sub in this regard. There are plenty of watches with similar if not better spec at fraction of Sub’s price tag but people buy it anyway just to own a Rolex 🙂

      • dennis

        I’m talking dollar value, you can buy a Sub today and the value will
        increase further in the future, the MM300 will not. I am a big Seiko
        fan, own many, new and vintage.

        • I think MM300 prices will go up as well. I got mine SBDX001 in 2015 preowned for about ~$1200 and I didn’t even try to get the lowest price possible. Now, the cheapest MM300 on Watchrecon is $1575.

          http://www.watchrecon.com/?query=mm300

  • Mike V

    Why did you remove my comment and your reply? I feel both made good points for your readers to think about and isn’t that the point of all this?