Seiko Marinemaster SLA079 Review: The Deep Sea for Normal Humans

Quick Take:
The SLA079 brings the Marinemaster name back into focus with sharper casework, a Grand Seiko adjacent movement, and proportions that make it surprisingly wearable. It doesn’t try to replace the big, heavy legends like the SLA023, a watch I still adore, but instead offers a balanced daily-wear diver that feels just as serious without the bulk. If you’ve ever wanted a Marinemaster that wears like an SKX but carries the DNA of Seiko’s greatest hits, this is it.

A Long Love Affair With Seiko Divers

Let me start with a confession: I’ve always loved Seiko divers. I still wear my Turtle all the time, and my SLA023 Marinemaster 300 isn’t going anywhere. That watch has everything I love about Seiko, unapologetic size, tool-first build, and enough heft to remind you you’re wearing something serious. Some people call it a brick, but not me. On my 7.5-inch wrist, it feels like home.

So when the SLA079 was announced, I didn’t hesitate. I ordered mine from Arizona Fine Time, like I do with most of my nicer Seikos. I wasn’t chasing specs; I just wanted to see what Seiko would do with the Marinemaster name after years of tinkering with reinterpretations and SPB divers.

The result? A watch that surprised me. The SLA079 isn’t a replacement for the old MM300, it’s a companion. It’s slimmer, easier to wear, and tuned for daily life. But it still feels like a Marinemaster.

The Case: Serious DNA, New Wearability

Seiko sized this one at 42.6 mm wide and 13.4 mm thick, with a lug-to-lug just shy of 50 mm. That’s not small by any means, but compared to the old MM300s, it’s a trim, balanced package. On the wrist it hugs close, thanks to Seiko’s clever undercutting and beveled midcase.

The finishing is excellent. You get brushed surfaces where you want tool vibes and Zaratsu style polished bevels where you want the light play. The case sides have that jewel-like sharpness that’s always been Seiko’s ace up the sleeve.

The big upgrade here is the screwed-in crown tube. Older Marinemasters had pressed tubes, fine until something went wrong, then you were staring at a case replacement. The SLA079’s replaceable crown tube means you can service this watch for decades. That’s a generational upgrade, the kind of detail that doesn’t show in photos but matters when you actually use your watches.

Dial & Proportions: Almost Perfect

The dial is a matte black with a grainy texture, giving contrast to the polished markers and brushed polished handset. It’s not flashy, and I like that. This watch is supposed to be about legibility and presence, not glitter.

That said, I’ll admit something: every once in a while, the proportions throw me off. Maybe it’s the chapter ring. Maybe it’s how the textured dial and glossy bezel insert interact. Sometimes, at the wrong angle, it just looks slightly odd. Not enough to ruin it, but enough to make me glance twice.

Still, 99 percent of the time the SLA079 looks fantastic. The indices pop, the date at 4:30 blends in well, and while purists still complain about the Prospex X, I’ve made my peace with it. If a letter X on the dial ruins a watch for you, that’s on you.

Bezel & Lume: Familiar Territory

Seiko bezels are a mixed bag, but this one’s good. It’s a 120-click unidirectional bezel with coarse knurling that’s easy to grip, smooth action with just enough resistance, and no real alignment drama unless you force it. The insert is lacquered steel, not ceramic, but it looks the part and keeps the utilitarian character intact.

The lume? Classic Seiko LumeBright. Bright, even, long-lasting. It beats the SPB divers easily, though I’m not sure it surpasses every old MM300. Still, when the lights drop, the SLA079 glows like a torch, exactly what you want from a professional diver.

The Movement: In-House Credibility

Inside ticks the 8L35, essentially a Grand Seiko movement without the finishing. Hand-assembled in the same workshop, running at 28,800 vph with a 50-hour power reserve, it’s a movement that gives the Marinemaster credibility.

This is where the SLA079 separates itself from the SJE reinterpretations. I reviewed the SJE101, and while it’s a beautiful watch, it isn’t a true Marinemaster. Two hundred meters of water resistance and the 6L movement put it in a different league. The SLA079 carries the weight of the 8L, and that matters.

Bracelet & The Clasp Letdown

Here’s the part that bugs me. For a $3,000 watch in 2025, Seiko is still shipping these with a fold-over clasp and four micro-adjust holes. That’s it. No on-the-fly adjustment, no tool-less slider, nothing that lets you size the bracelet mid-day.

And yes, the bracelet itself is good. Solid links, comfortable taper, better proportions than the old MM300 bracelet with its long, awkward links. But the clasp is the one obvious flaw. Tudor figured this out. Rolex nailed it ages ago. Even microbrands are putting tool-less systems into their clasps.

How Seiko keeps missing this is beyond me. It doesn’t make the SLA079 unwearable, I’ve worn it plenty, but it’s the one reminder that Seiko still lags where it shouldn’t.

Real-World Use: Built to Be Worn

I don’t baby my watches, and the SLA079 hasn’t asked me to. I’ve worn it through humid South Carolina summer days, during yard work, and out running errands with the kids. I’ve swapped it onto a Tropic strap for the beach and onto NATO for some hiking. Every time, it feels tough, balanced, and dependable.

On bracelet it’s versatile enough for a restaurant or office setting. On rubber it feels like a throwback tool. This is a diver I can actually wear all day, every day, something I can’t honestly say about the SLA023. Don’t get me wrong, I love the 023’s heft and presence, but it’s not a watch I forget I’m wearing. The SLA079? I forget, until I glance down and smile.

Comparisons: Where It Stands

SJE101: Pretty, slim, dressy, but not a true Marinemaster. Two hundred meters of WR and a 6L movement don’t cut it for the name.

SLA023/MM300: Still one of my favorites, still the classic. Bigger, heavier, unapologetic. The SLA079 isn’t better, just more practical.

Rolex Deepsea: My buddy’s Deepsea is a beast. The SLA079 isn’t the same watch, but it gives you 90 percent of the serious diver feel for a fraction of the money. Deepsea for normal humans.

Oris Aquis / Diver 65: Great watches around $2,700, but running Sellita movements. The SLA079’s in-house 8L and Seiko history make it a stronger value.

Final Thoughts

The SLA079 isn’t perfect. The clasp is outdated, and once in a while the proportions feel a little odd. But this is easily one of the best modern Marinemasters Seiko has built.

It doesn’t try to erase the SLA023 or the older MM300s, and thank God for that. Those are legends in their own right, and I still love them. What the SLA079 does is make the Marinemaster name wearable for the long haul. It’s tough, balanced, and versatile without losing the DNA that made the original Marinemaster iconic.

At just under three grand, it’s also a smart value. Positioned above the SPBs and below the LX Spring Drives, the SLA079 gives you real Seiko heritage, serious specs, and everyday usability.

For me, it’s the Marinemaster I’ll wear when I want the soul of the legend without the bulk of the brick. And that’s why it’s staying in my rotation.

Verdict: Not a replacement for the SLA023, but the most balanced, most wearable Marinemaster yet.