The Blancpain Fifty Fathoms 70th Anniversary Act 1 Series I, reference 5010A 1130 NABA, is a limited-edition stainless-steel dive watch announced in 2023. Its defining specifications are a 42.30 mm case, 30 bar water resistance and automatic Calibre 1315 with a five-day power reserve. Blancpain announced three regional runs of 70 pieces each, for 210 watches in Act 1. This review assesses what the published specifications and launch information establish; it does not claim independent wear or performance testing.
What the Act 1 Series I is
Blancpain positions Act 1 as the present-focused part of its 70th-anniversary program: a tribute to the contemporary Fifty Fathoms rather than a reissue of an early model. The manufacturer says it launched the Fifty Fathoms in 1953 and describes it as “the first true diving watch”; that is Blancpain’s own historical characterization. The brand’s anniversary overview contrasts Act 1 with Act 2, oriented toward the future, and Act 3, oriented toward the past. Blancpain’s January 1, 2023 Act 1 announcement and its anniversary overview provide that framing.
The product listing identifies Series I as reference 5010A 1130 NABA. Blancpain announced three regional Series I/Act 1 editions—EMEA, Asia-Pacific and the Americas—with 70 pieces per region. That yields an announced Act 1 total of 210. The announcement confirms the regions and quantities but does not map each region to a particular Series I, II or III reference, so the regional allocation should not be inferred from the reference suffixes. The official Series I product page identifies the reference.
Case, dial and bezel specifications
The official product page lists a stainless-steel case measuring 42.30 mm in diameter and 14.30 mm thick. Blancpain’s launch announcement rounds the diameter to 42 mm; 42.30 mm is the more precise figure on the model listing. The watch has a sunburst black dial, a unidirectional rotating bezel with a curved sapphire insert, and a sapphire caseback. Blancpain describes the dial as having contrasting luminous indications. These are brand-published design and specification details, not independent observations of legibility or lume performance.
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- Blancpain Fifty Fathoms Chronograph Automatic Men's Watch 5200-1110-NABA
- Case: stainless steel, 42.30 mm diameter and 14.30 mm thick.
- Dial: sunburst black, with luminous indications as described by Blancpain.
- Bezel: unidirectional rotating, with a curved sapphire insert.
- Water resistance: 30 bar, as listed by Blancpain.
- Caseback: sapphire.
The 30 bar figure is the manufacturer’s stated water-resistance rating. It should not be read as a report of independent testing or as a substitute for following Blancpain’s operating and service guidance.
Calibre 1315 and the five-day reserve
The watch uses Blancpain’s automatic Calibre 1315. The brand lists a 120-hour power reserve—five days—along with a 4 Hz frequency, 35 jewels, a silicon balance spring and 227 components. Blancpain’s launch announcement attributes the extended reserve to the movement’s three-barrel design. The figures describe the published movement specification; no independent timing or reserve test is established here.
Strap and fit considerations
Blancpain lists a fabric NATO strap with a pin buckle and says the strap is interchangeable. The listed distance between the horns (the lugs) is 21.50 mm. A nominal 21 mm NATO strap is therefore a plausible accessory search, but the listing does not certify aftermarket straps; check actual width, thickness and fastening compatibility before buying. No third-party strap should be assumed to be Blancpain-approved based on these dimensions alone.
Edition, U.S. listing and availability
On Blancpain’s U.S. product page, the Series I was listed at $21,600 and marked “Sold out” when checked on October 8, 2026. Those are a dated snapshot of the brand’s U.S. listing, not an independent valuation, a current secondary-market price, or evidence of worldwide availability. For a current purchase inquiry, check the official listing or contact an authorized seller; availability may differ by region and change over time. Blancpain Series I listing.
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- Applied polished rose gold hour markers with luminous fill.
- 5015-3603C-63B
What this review can—and cannot—say
The available evidence supports a clear picture of the Series I’s identity, construction, movement specification and announced edition size. It does not establish how the 42.30 mm case wears on different wrists, how accurately a particular example keeps time, how bright its lume appears in practice, or how it performs in water. Those judgments require hands-on or instrument testing, so they should not be inferred from the specifications.
For readers choosing among the anniversary acts, Blancpain’s own distinction is straightforward: Act 1 is the contemporary tribute, Act 2 looks toward future-facing technical diving through the Tech Gombessa, and Act 3 looks back to vintage design. That is the manufacturer’s program framing, not a direct specification comparison between these watches. Details are in the official anniversary overview.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
