10 Days with the Seiko MM300

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If you follow me on Instagram (@vintagediver), you’ll probably have seen that I recently took a vacation to Puerto Rico (yes, it was freaking awesome). You may also have noticed that I’m a “vintage guy” when it comes to watches. Normally I tend to wear a different vintage watch each day, although I have been know to wear the same watch for a few days in a row (crazy, I know), especially if it’s my ’79 Tudor blue snowflake.


Now, I know lots of you guys will pack several watches for a trip but I don’t like the idea of traveling with a bunch of my watches, having to worry about taking them on a plane or leaving them in the hotel. So, I will usually pick one watch for my trip and just have to suffer through the withdrawals. Since this vacation was to a hot and humid tropical locale and I knew I’d be spending lots of quality time in the pool and ocean, I chose to go with a modern watch with a screw-down crown: The Seiko SBDX001 Marine Master 300m, or MM300 as it’s commonly known. The MM300 comes on a great bracelet, but I chose to wear it on an Isofrane strap for comfort in the muggy weather, plus it just looks killer on that strap.


As a result of my choice I ended up wearing the same watch, a modern watch, for TEN DAYS STRAIGHT! Amazingly the world did not end, nor did I implode! Actually, I was very happy with my choice and really became quite attached to the MM300.  I’ve always loved this watch, and it has fast become my favorite modern watch. Of course, it’s a modern ‘heritage’ version of the vintage 1960’s Seiko 6159-7000/1, which is a timeless classic and one of my all time favorite vintage watches. It’s at the top of my ‘must have’ list, but sadly still eludes me.


The MM300 is big but not huge, measuring 44mm wide (42mm across the bezel). It is a bit on the thick side at 14.6mm, and as such it does sit kind of high on the wrist. I’ll admit this was a small concern for traveling as I didn’t really want to bang it on stuff on the plane and such (yes, I’m that kind of collector). That said, the MM300 really wears well on the wrist, and its height wasn’t an issue at all.  Never banged it on anything, and didn’t end up with any scratches or dings (whew!). The size and weight are very comfortable, especially on the Isofrane, which is quite simply the best and most comfortable rubber strap on the market, bar none.

The MM300 is also quite versatile, going from the pool or beach to a nice dinner at a fancy restaurant with ease. Now, it’s no Patek Calatrava, but it is nice enough looking and not too “toolish” to wear out for a nice dinner. Not sure how well it would fit under a cuff with a sport coat, but I don’t wear sport coats unless I absolutely HAVE to. And since Puerto Rico in September is hotter than Hell on a bad day, I definitely did not pack my sport coat.



I wore the MM300 every day, from the moment I got up to the moment I went to bed. I wore it bike riding, hiking, in the pool, at the beach, and yes, even in the shower (the horror!). It easily handled the transition from 90 degree temperature and 90% humidity to the cool air conditioned hotel room and back outside several times a day with no ill effects.  As could be expected from a professional divers watch, it performed admirably under all these extreme conditions (that’s sarcasm boys and girls).

Once I landed in the Eastern Time Zone and had set it, I didn’t unscrew the crown once. With a 50 hour power reserve,  the watch stayed wound and sealed and ran the whole time as it should, keeping near perfect time. As a guy who lives on the central coast of California where the weather doesn’t vary much, it was definitely a departure for me to have the high heat and humidity.


Normally I really enjoy the variety and novelty of wearing a different vintage watch each day. I wear them carefully, taking care not to get them wet or whack them on the door handle. However, I have to admit it was kind of nice just strapping on the MM300 in the morning and not worrying about it from that point on. Sure I’m cautious to not smack into something, but that’s become an ingrained habit (like most of you I’m sure). Other than that I only really thought about it when looking to tell the time, or when I was shooting a picture of it (yep, did lots of that….watch nerd!) in the various exotic locales.

So, what did I learn over my ten days with the MM300? Quite a bit to be honest. I learned that first and foremost I LOVE this watch. It’s everything I want in a modern watch. It’s comfortable, reliable, robust, versatile and stylish. Everything a WIS could need on a vacation, or at home for that matter. Plus it’s pretty damn photogenic, which comes in handy when you’re an Instagram addict. It is built like a tank, but beautiful enough to wear anywhere. The combination of that sweet glossy bezel and the chunky steel case with its brushed and polished surfaces is truly a work of art. While I did miss all my vintage lovelies, the MM300 made it tolerable. I also learned that I can indeed wear a modern watch for an extended period of time and I will live to tell the tale…

Images from this post:

Christoph (Instagram’s @vintagediver) is a long time collector and lover of all things vintage, starting with comic books when he was a kid (he still collects them). His passion for watches began in 1997 when he was gifted a family heirloom vintage Omega Genève by his step-father. That started him on the watch collecting path—buying and selling vintage watches of all sorts, with a special appreciation for vintage dive watches and Seiko.

  • Elliott

    Such a beautiful watch! I don’t know where this world would be without Seiko divers.

  • Dr. No

    $2k for a Seiko? Lol.

    • wkfink

      Seiko make some of the best divers in the world. I know a couple professional divers (i.e. they dive for a living), and both of them own multiple Seikos.

      If I didn’t own an Omega, I’d own a MM300 or similar for sure.

    • Ignorance is bliss…

    • Richard


    • thievesarmy

      lol… u got a lot to learn “Doc”

    • PABLO T.


    • Joe0000

      Imagine your surprise when you find out there are lots of model over $8,000.00!

  • Great write up, Stoph. Maybe on my next trip, I’ll try taking one watch…

  • wkfink

    I’ve been a one-watch guy for a while. I wear my SMP every day, though that’ll change in a few days when I finally get my 3590.50 Speedmaster.

    I really like only having one watch; it’s nice to not have to make the decision of what watch I’ll wear on any given day, and having it be a diver means that no matter what, you’re ready for whatever life throws at you.

    I really like the MM300, though I really wish it was thinner.

    Great write-up!

  • Nikita

    One of the best men’s watch, true companion in any part of the world, any situation, any circumstances.

  • Dennis T.

    I need to compliment your photography…amazing images!

  • Great write up, fantastic pictures! A great watch truly stands the test of time (and travel), this one definitely proved that plus some…

  • FJM

    Personally, I’d go Squale 50 Atmos over the Seiko MM300.

    • wkfink

      The finish and overall quality of the pieces can’t even be compared; the MM300 is a much better diver.

    • PABLO T.

      Very different watches.

  • Love my Seiko divers!

  • ZP

    Great and thanks for the article!

    Love my mm300, one of the few folks (it seems) that like the stock OEM strap.

    I’ve heard that the SBDB009 strap is even better than the Isofrane strap (which I have on my SBBN015). Would love to see your take if you get to handle a SBDB009 in the future!


  • Leonard Martinez

    I can’t get over the simple beauty of the bezel and dial. My eyes do not park themselves on any particular feature. They study the incredibly pleasing hour markers. They ruminate over the shiny black bezel. They run up and down the minute and hour hands and often catch a ride on the second hand. The brushed and polished case titillates the optic nerve, and I love to play with the extension on the bracelet. What a pleasant ticking it makes, as does the bezel. And the lume? It’s a Seiko. What more need be said? This watch is the archetype of exquisite functionality.

  • dskul

    The writer of this article mentioned that his modern watch was a re-make of a watch originally made in the 60’s. I purchased this Seiko in Taiwan when I was in the Navy in 1973. I wore it every day for many many years before it stopped working. I have tried to have it repaired several times but even though I have spent hundreds of $, none of the repairs have lasted more than 3-4 months before the watch stops again. No warranty on the work. I tried to have Seiko repair and they refused. I was told by one repair shop that they couldn’t work on it because the hands and dials were coated with a radioactive substance. I have a lot of years with this watch, wore it all over the world (and it shows) and would like to get it running again. If possible I would like to get the whole watch restored; new crystal, face cleaned, case scratches removed if possible, etc. Any advice would be helpful.

  • JM

    @dskul try SCWF (Seiko Citizen Watch Forum) google it, join and ask about a reputable repair source. I will not reccomend any because I haven’t used one in years. You can gether info and make an educated decision. Good luck!

  • Pete Mustard

    What is the size of your wrist? Great review btw.

  • PABLO T.

    This article gave me the itch to get a mm300 when I read it about a year ago. Finally picked up an sbdx017 this week. Love it!

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