Seiko mm300 Marine Master review

Seiko mm300 Marine Master – Updated Review 2024

Curious about how the Seiko mm300 Marine Master compares in 2024 then we explore this discussion in-depth in this guide.

Since stepping foot into the watch industry, Seiko has remained true to its dream and has continued to roll out quality watches that are not just a gem in Japan but also loved worldwide.

Some of their iconic timepieces have enjoyed huge patronage from loyal and dedicated fans who love the feel and aura that Seiko watches bring with them.

Without mincing words, Seiko makes some of the best iconic dive watches you’ll ever come across, so it’s no surprise to see watch lovers queuing up to lay their hands on the new Suma, Turtle Reissue, the Tuna models, and the famous SKX173/SKX007, which all fall under the Prospex banner.

Even though the Prospex line has many fine watches to its name, the Iconic Marine Master 300 sits at the top of the heap, and that’s all thanks to its performance and brilliant specification.

For starters, the Seiko brand is viewed by many watch lovers as a budget-friendly brand, despite offering myriads of super high-end timepieces.

So with the MM300, you get a budget-friendly watch with high-end specs that will give popular watches like Hamiltons and Swiss Luxury watches a run for their money.

But before giving you all the juicy details about the MM300, let’s give you a brief history of the Seiko brand.

About the Seiko brand

Seiko has remained consistent in its goal of rolling out iconic watches with huge appeals.

Even after many years in the watch industry, they still compete with other popular watch brands globally,

Since the brand kicked off in Ginza, Tokyo, in 1881, they haven’t taken their foot off the pedal and have consistently released high-end watches that showcase Japanese craftsmanship.

Even though Seiko originally started off repairing and selling watches, the company evolved into a full-fledged watch brand when it began its factory in Seikosha in 1892.

Their first pocket watch, the Timekeeper, was the start of many good things to come for the company, and that’s because the watch enjoyed massive success, especially being the first pocket watch of that era.

Following the massive success enjoyed by Timekeeper, the company followed up with the launch of their very first watch to have the Seiko brand name in 1923.

Today, Seiko is still highly revered by watch lovers, not just for their vintage collections but also for their new watches.

Popular specifications

  • Crystal: Dual curved Hardlex
  • Lug-to-lug measurement: 48.4mm
  • Water-resistance: 300
  • Power reserve: 50 hours
  • Movement: Seiko 8L35 Automatic
  • Diameter: 44.3mm (including the shroud)

Seiko MM300 (seiko mm300 sbdx001, seiko mm300 sbdx017, seiko mm200)

Besides having lots of impressive specs, Seiko MM300 is a little on the big side.

But even though it looks big and wears big, big isn’t such a bad thing when it comes to Seiko watches as they are designed to fit perfectly.

As per the Seiko MM300 dive watch, there are two variations, the Seiko MM300 SBDX001 and the Seiko MM300 SBDX071.

While both watches are high-end and all shades of amazing, the only noticeable difference between them is their bracelets.

While the SBDX001 comes with a rubble strap, the SBDX017 features Seiko’s signature stainless steel bracelet.

That said, both watches perform exceptionally well in the most extreme conditions.

Comparing both watches to the Seiko MM200, you’ll agree that Seiko MM200 doesn’t come close.

While Seiko MM300 is water-resistant up to 300mm, Seiko MM200 is resistant only up to 200mm.

Seiko MM300 Movement

Seiko MM300 is powered by Seiko’s signature 8L35 Automatic movement.

Because this movement is built for performance and reliability, it works exactly as designed.

With this movement, you can expect a +3.4 seconds per day, which meets the average daily rate of -4/+6s per day.

Seiko MM300 Case

Seiko MM300 comes with a spectacular case that gives it some unique personality.

Thanks to its stylish Monoblock case, this watch looks every inch luxurious and high-end.

Its monoblock case means that everything within the watch is fitted via the front and subsequently sealed off using crystal.

This explains why there is no removable back with the Marinemaster 300.

Though it is a bit unusual to have a dive watch with this design, the purpose is to eliminate one point where water can get through.

Away from its monoblock casing, Seiko MM300 wows you with its fine finishing, beautiful transitions, mesmerizing touches, and crisp lines.

We love that its steel casing is coated with Seiko’s signature Diashield.

Like other materials used in Seiko’s dive watches, Diashield is designed to be scratch and wear-resistant.

Away from its case, Seiko MM300 features a signed crown that is nicely fitted at 4 o’clock.

Not just that, we are particularly impressed by this watch’s smooth winding action.

Because this watch has its crown placed at 4 o’clock, it is gentle and won’t dig into your hand as you continue to use it.

Seiko MM300 Dial

Seiko Marinemaster 300 features a unique design that Seiko fanatics have come to love.

And because it features hour indices that are lumed, you can easily tell the time even in the most extreme conditions.

Seiko Marine Master 300 dial

For starters, this watch has its 6 and 9 o’clock markers rectangular, while the accompanying intermediate hours are somewhat rounded.

While the 12 o’clock hour markers appear angled, all markers have a very visible lume, which has been praised for glowing brightly, even on very bright days.

Even though the dial is painted white, it looks matte black and legible.

Seiko MM300 Bracelet

Where Seiko is a bit lacking is with their bracelet.

That said, the Seiko MM300 features polarizing bracelets.

So if the bracelet fits you, it fits nicely.

More so, we particularly love that the bracelet for Marinemaster 300 is quite long and doesn’t articulate in the middle, as you’ll notice with other brands.

This makes for a comfortable wearing experience.

Thanks to its ratcheting diving extension, the clasp for the marine master is easy to activate.


  • Classy finishing and top-notch design
  • The movement and dial is one of a kind
  • Impressive tool watch


  • It is somewhat heavy and thick.
  • The bracelet scalp can do with some improvement.
  • Its bezel design and finishing are prone to scratches.

Frequently asked questions

How reliable is the MM300?

Designed for extreme performance, the Seiko MM300 will live up to its promises.

Its rugged design means it can be used in the most extreme environment.

At 300mm, this watch still performs superbly compared to other dive watches in this category.

How much does MM300 cost?

For a watch that is above the $1000 price mark, you’ll agree that this watch is super expensive.

That said, the watch lives up to its expectations, so it’s worth every penny spent purchasing it.

What type of movement does it use?

The MM300 is powered by Seiko’s signature 8L35 automatic movement.


The Seiko MM300 will make a worthy addition to your watch collection, especially if you have a thing for dive watches.

And trust us when we say it is one of those perfect day timepieces that will see you through any event.

With this watch gracing your wrist, you can walk around with all the confidence you can muster.