The Seiko Prospex Marinemaster SLA077 and SLA079 are 2024 300-meter automatic divers based on Seiko’s 1968 professional diver. They share the same substantial 42.6 mm case, Caliber 8L35 movement, sapphire crystal, and $2,900 U.S. list price. The buying decision is mainly aesthetic: SLA077 brings a silvery-white dial, while SLA079 delivers the traditional black, high-contrast dive-watch look.
The Seiko Prospex Marinemaster SLA077 and SLA079 are 2024 additions to Seiko’s flagship diver collection. Both are 300-meter automatic dive watches based on the design of Seiko’s 1968 diver, and both use the Japanese-made Caliber 8L35. Their specifications are essentially shared; the important buying decision is the dial. The SLA079 has a conventional, high-contrast black dial, while the SLA077 uses a more distinctive silvery-white dial.
Neither reference should be treated as merely a cosmetic fashion variant. Seiko has built the pair around a tool-watch brief: a 300-meter rating, unidirectional timing bezel, sapphire crystal, screw-down crown, strong luminous treatment, and a movement intended for diver’s watches. They are also large and heavy mechanical watches, so the published dimensions matter as much as the heritage story.
What are the Seiko Marinemaster SLA077 and SLA079?
The SLA077 and SLA079 are modern Marinemaster interpretations of Seiko’s 1968 professional diver. Seiko’s original 1968 model combined a high-beat automatic movement with 300-meter water resistance, a one-piece case, a screw-down crown, and a unidirectional rotating bezel. The new watches retain that period-inspired case language and water-resistance figure while updating the materials, crystal, finishing, and movement.
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- WATER-RESISTANT: these water-resistant men's dive watches are ISO scuba-approved to depths of 200 meters
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- STAINLESS STEEL: features a durable 43.8mm stainless steel watch case and bracelet.
- LUMIBRITE DISPLAY: this men's automatic watch features a highly-legible display with LumiBrite hands and markers
- 4R35 CALIBER: equipped with the reliable caliber 4R35 automatic movement, this accurate men's watch keeps precise time
Seiko announced both watches as new creations for the Marinemaster collection, with availability beginning in September 2024. The current U.S. Marinemaster collection places both models at $2,900. That is a U.S. list price; regional pricing is not directly interchangeable. For example, the UK boutique listing for the SLA079J1 is £2,580.
SLA077 versus SLA079: what is the difference?
| Feature | SLA077 | SLA079 |
|---|---|---|
| Dial | Silvery-white, patterned dial | Black dial with a subtle sand-like pattern |
| Legibility character | More unusual and visually distinctive | Traditional high-contrast dive-watch appearance |
| Movement | Seiko Caliber 8L35 | Seiko Caliber 8L35 |
| Water resistance | 300 meters | 300 meters |
| Crystal | Dual-curved sapphire with inner anti-reflective coating | Dual-curved sapphire with inner anti-reflective coating |
| Bracelet | Stainless steel | Stainless steel |
| U.S. list price | $2,900 | $2,900 |
The Seiko Prospex Marinemaster SLA079 is the straightforward choice if you want the familiar black-dial dive-watch formula and the strongest visual contrast. The Seiko Prospex Marinemaster SLA077 is the more distinctive option, using its light dial and texture to give the historically shaped case a less conventional appearance.
That distinction is primarily aesthetic rather than a documented difference in underwater performance. The two watches share the same published case, bezel, crystal, movement, water-resistance rating, bracelet type, and core functions.
Case dimensions and wearing implications
Both watches measure:
- Diameter: 42.6 mm
- Thickness: 13.4 mm
- Case length: approximately 49.3 mm
- Lug width: 20 mm
- Case material: stainless steel
The SLA079 is listed at approximately 196.0 grams, and the SLA077 is built on the same substantial platform. On paper, these are large, heavy mechanical dive watches rather than compact everyday divers. Whether the proportions work for a particular wrist depends on wrist shape, tolerance for weight, and how the roughly 49.3 mm case length sits across the wrist. Published dimensions cannot establish personal comfort, so prospective buyers should compare them with a watch they already wear or try one on.
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The case has the angular profile associated with Seiko’s 1968 design reference, with polished surfaces integrated into the broader tool-watch form. The crown is positioned at approximately 4 o’clock. Seiko also highlights improved knurling on the bezel and crown, intended to provide a more secure grip.
One unusual construction detail is the crown arrangement. The crown is secured through a separate component built into the case rather than being screwed directly into the case itself. Seiko says this approach can make crown replacement easier. That is a serviceability claim from the manufacturer, not a guarantee of lower maintenance cost or easier servicing in every market.
300-meter dive-watch equipment
Sapphire crystal
The crystal is dual-curved sapphire with anti-reflective coating on the inner surface. Sapphire provides the scratch resistance expected at this price and is paired with the internal coating to help preserve dial visibility. The dual curve continues the shaped, heritage-oriented appearance rather than using a completely flat crystal.
Rank #2
- STAINLESS STEEL CASE built to endure with style, making this watch your perfect daily companion
- AUTOMATIC MOVEMENT for seamless precision in every tick of this watch
- SCRATCH-RESISTANT CRYSTAL to maintain a pristine look even with daily wear and tear on your watch
- LUMINESCENT HANDS for effortless readability in low-light conditions, ensuring you never miss a moment with this watch
- WATER RESISTANT DESIGN ensuring your watch is ready for any adventure, rain or shine
Unidirectional bezel
The bezel rotates in one direction and carries a 60-minute scale for dive-time measurement. Seiko’s boutique description presents its design as consistent with ISO diving standards. That wording should not be expanded into a claim that every aspect of the watch has independently documented ISO certification unless the relevant certification is specifically established.
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Both references have a screw-down crown and screw case back. Together with the case construction and 300-meter rating, these features position the SLA077 and SLA079 as serious recreational and professional-style dive watches rather than dress watches with superficial dive styling.
Lumibrite and dial design
Seiko emphasizes high legibility through applied indices, controlled dial colors and textures, and high-intensity Lumibrite on the hands and indexes. The SLA079’s black dial creates the most immediately familiar contrast. The SLA077’s silvery-white dial is more unusual, but its applied markers and luminous treatment preserve the functional layout.
The SLA079 has a subtle sand-like pattern on its black dial. Independent technical coverage describes the SLA077’s light dial as silvery white and patterned. Both watches include a date display, which adds daily practicality but also gives the dials a less purely minimalist appearance than a no-date professional diver.
Caliber 8L35: the movement inside
Both references use Seiko Caliber 8L35, an automatic movement with manual winding and a stop-seconds function. The official specifications list:
- Jewels: 26
- Power reserve: approximately 50 hours
- Stated accuracy: -10/+15 seconds per day
- Functions: hours, minutes, central seconds, date, and stop seconds
- Manufacturing context: crafted at the Shizukuishi Watch Studio in Iwate, Japan
The 8L35 is important to the Marinemaster’s position in the Prospex range. It is described by Seiko as a robust caliber made for diver’s watches and separates these models from less expensive Prospex divers using more widely deployed movements. That does not justify calling it “Grand Seiko-grade,” hand-finished, or equivalent to a particular Grand Seiko caliber; those claims are not established by the available official documentation.
There is a small published specification conflict concerning frequency. Seiko’s current UK boutique page lists 28,000 vibrations per hour, while specialist secondary coverage commonly lists 28,800 vibrations per hour, or 4 Hz. The safest treatment is to use the official current retailer figure when quoting the product page, or simply omit the frequency. The discrepancy does not change the practical buying choice between the SLA077 and SLA079, since both use the same caliber.
Rank #3
- WATER-RESISTANT: these water-resistant men's dive watches are ISO scuba-approved to depths of 200 meters
- AUTOMATIC: these self-winding, automatic men's watches are powered by your movement, with a power reserve of 41 hours
- LUMIBRITE DISPLAY: this men's dive watch features a highly-legible display with LumiBrite hands and markers
- STAINLESS STEEL: features a durable stainless steel watch case and bracelet, unique case shape resembling teeth, and PADI red and blue colors on its elapsed timing bezel
- 4R36 CALIBER: equipped with the reliable caliber 4R36 automatic movement, this accurate men's watch keeps precise time
Bracelet, lug width, and strap options
Each watch is supplied on a stainless-steel bracelet with a three-fold clasp, secure lock, push-button release, and extender. The bracelet is appropriate to the watches’ dive-oriented positioning and adds to their substantial overall weight.
The stated 20 mm lug width creates a clear accessory opportunity for owners who want a different look or a lighter setup. A 20 mm dive watch strap or 20 mm NATO strap may be worth considering, but “20 mm” alone does not guarantee compatibility. Before buying, check:
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- the shape and thickness of the strap near the lugs;
- case clearance and whether the strap rubs against the case;
- the bracelet’s end-link geometry; and
- the clasp or buckle arrangement.
A watch spring bar tool can help with bracelet or strap removal, but changing a high-value watch is not risk-free. Scratched lugs, bent spring bars, and an incorrectly seated bar can all create problems. Owners without experience should use a watchmaker or have the work performed by a reputable dealer rather than treating a tool as a requirement for a guaranteed DIY job.
Which Marinemaster should you buy?
Choose the SLA079 if you want:
- the classic black-dial dive-watch appearance;
- the most immediately obvious contrast between dial, markers, and hands;
- a versatile look that stays close to conventional professional diver design; and
- the central product reference most readers will recognize when searching for the black Marinemaster.
Choose the SLA077 if you want:
- a silvery-white dial rather than another black diver;
- a more visually distinctive interpretation of the 1968-derived case;
- the same 8L35 movement and 300-meter specification as the SLA079; and
- a watch whose dial is less conventional while remaining clearly tool-oriented.
There is no documented technical advantage in selecting one over the other. The choice is about dial color, texture, and how conventional or distinctive you want the watch to look. Both should be evaluated as sizeable 42.6 mm watches with a 13.4 mm thickness and a steel-bracelet weight approaching 200 grams.
Price and lineup position
Seiko’s U.S. Marinemaster collection currently lists the SLA077 and SLA079 at $2,900 each. The collection identifies Marinemaster as Seiko’s flagship diver series and also includes newer HBF001 and HBF002 Marinemaster references. The SLA077 and SLA079 therefore sit above many mainstream Prospex divers in both price and movement positioning.
Availability and pricing vary by region. The UK listing identifies the black model as SLA079J1 and currently shows £2,580. Buyers should compare the price in their own market, confirm whether a seller is authorized, and check the exact regional reference before ordering. Neither model should be called a limited edition, discontinued, sold out, or investment-grade watch based on the information currently available.
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Specifications at a glance
| Specification | SLA077 and SLA079 |
|---|---|
| Collection | Seiko Prospex Marinemaster |
| Design basis | Reinterpretation of Seiko’s 1968 diver |
| Case | Stainless steel |
| Diameter | 42.6 mm |
| Thickness | 13.4 mm |
| Case length | Approximately 49.3 mm |
| Lug width | 20 mm |
| Water resistance | 300 meters |
| Crystal | Dual-curved sapphire with inner anti-reflective coating |
| Bezel | Unidirectional, 60-minute dive scale |
| Crown | Screw-down, positioned at approximately 4 o’clock |
| Movement | Seiko Caliber 8L35 automatic |
| Winding and seconds | Manual winding and stop seconds |
| Jewels | 26 |
| Power reserve | Approximately 50 hours |
| Accuracy specification | -10/+15 seconds per day |
| Magnetic resistance | 4,800 A/m |
| Bracelet | Stainless steel with three-fold clasp, lock, push buttons, and extender |
| Weight | SLA079 listed at 196.0 g |
| U.S. price | $2,900 |
Verdict
The Seiko Prospex Marinemaster SLA077 and SLA079 are substantial, heritage-based 300-meter divers whose strongest technical selling points are the 8L35 movement, sapphire crystal, clear dive bezel, strong lume, and purpose-built case architecture. They are not small or lightweight watches, and their stated movement accuracy is ordinary mechanical-watch territory rather than a promise of quartz-like precision.
Rank #4
- KHAKI GREEN DIAL: this rugged sports watch features a khaki green dial patterned to mirror the shape of the bezel’s edge, with Lumibrite dial indicator hands and markers for low light and a magnified day/date calendar
- BLACK BEZEL: this versatile men’s watch features a black ceramic unidirectional bezel with distinctive scalloped edging, for elapsed timing
- AUTOMATIC & MANUAL: SRPE05 automatic watches for men power up with your natural movements, and feature the ability to wind manually, with 41 hours of reserve power
- WATER-RESISTANT: these rugged stainless steel dive watches for men feature a khaki green silicon strap, and are both stylish and robust, following ISO standards for scuba, and are water-resistant to 200 meters
- 4R36 CALIBER: equipped with the reliable 4R36 caliber, these precise men’s wrist watches ensure the most accurate timekeeping
Buy the SLA079 for the familiar black, high-contrast tool-watch look. Buy the SLA077 for the silvery-white dial and more distinctive visual identity. Since the price and specifications are shared, the best choice is the one whose dial you will still want to wear after the heritage appeal has faded.
Frequently Asked Questions
What is the difference between the Seiko SLA077 and SLA079?
No. The two watches share the same published core specifications, including the 300-meter rating, Caliber 8L35 movement, sapphire crystal, bezel, case dimensions, and bracelet. The meaningful difference is the dial: the SLA077 is silvery white, while the SLA079 is black.
How much do the Seiko Marinemaster SLA077 and SLA079 cost?
The official U.S. Marinemaster collection lists both models at $2,900. Regional prices differ; for example, the UK boutique listing for the SLA079J1 is £2,580. These prices should not be converted directly without considering taxes, distribution, currency, and local market pricing.
Are the SLA077 and SLA079 proper dive watches?
Yes. Both models have a published 300-meter water-resistance rating, a screw-down crown and case back, and a unidirectional bezel with a 60-minute scale. Their specifications support their positioning as serious dive watches, although buyers should follow normal professional dive-watch inspection and maintenance practices.
Can I fit any 20 mm strap to the Seiko Marinemaster?
The published lug width is 20 mm, but not every 20 mm strap will fit. Check spring-bar dimensions, end-link geometry, strap thickness near the lugs, and case clearance before ordering an alternate strap.
What is the frequency of the Seiko 8L35 movement?
The official UK boutique specification lists 28,000 vibrations per hour. Some specialist secondary coverage lists 28,800 vibrations per hour, or 4 Hz. Because those published figures conflict, the official current product specification is the safer figure to quote.
The Bottom Line
Bottom line: The SLA077 and SLA079 share the same 42.6 mm, 300-meter case, Caliber 8L35 movement, sapphire crystal, bracelet, and $2,900 U.S. list price. Choose the SLA079 for conventional black-dial legibility; choose the SLA077 for a more unusual silvery-white presentation. The real caution is size: at 13.4 mm thick and approximately 196 g on the listed SLA079 specification, these are serious, substantial dive watches.
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