What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
This cannot honestly be presented as a hands-on review: there is no verified physical inspection or independent testing of the watch behind the available evidence. What can be reviewed is Alpina’s published specification for the green, no-date Seastrong Diver 300 Heritage, reference AL-520GR4H6, and how it differs from the date-equipped AL-525S4H6. Alpina lists a 42 mm case, 12.3 mm thickness, 21 mm lug width and 300 m/30 bar water resistance for the AL-520; those are manufacturer claims, not independently tested results.
Which Seastrong Diver Heritage is this?
The name covers distinct references, so confirm the reference before comparing specifications or prices. Alpina’s U.S. listing identifies the green, no-date watch as the AL-520GR4H6. The date-equipped AL-525S4H6 is a separate variant, not simply the same watch with a date added: Alpina’s UK page also describes a 60-minute internal rotating bezel for that reference.
| Reference | Configuration stated by Alpina | Published dimensions | Price observed 2026-10-07 |
|---|---|---|---|
| AL-520GR4H6 | Green dial, no date; 60-minute immersion-time scale | 42 mm case, 12.3 mm thick, 21 mm lug width | $1,995 on Alpina’s U.S. listing |
| AL-525S4H6 | Date; 60-minute internal rotating bezel | 42 mm case length, 12.3 mm thick, 21 mm lug width | $1,995 on Alpina’s U.S. listing; £1,595 on Alpina’s UK listing |
Dimensions and configurations above are manufacturer-published. The prices are market-specific listing observations, not guaranteed current prices; U.S. and UK amounts are not directly interchangeable.
What Alpina publishes for the green AL-520
For reference AL-520GR4H6, Alpina lists a stainless-steel 42 mm case, 12.3 mm thickness, 21 mm lug width, green dial, anti-reflective sapphire crystal, rubber strap, automatic AL-520 caliber, 38-hour power reserve and 300 m/30 bar stated water resistance. The page does not establish independent verification of these specifications or performance under use.
Free tools Windows power users keep installed
One-click scans. No signup required.
#1 Best Overall
- The Seastrong Heritage model is inspired by the 1960’s professional diver design, a beautiful re-issue of this historic model. This timepiece features an automatic movement with a 60-minute internal rotating bezel. It also has a textured rubber strap, vintage white and black dial, screw down crown and an engraved caseback to protect the movement from everyday elements.
- 300M water resistant with uni-directional turning 60m diving bezel
- AL-525 Caliber - Automatic Self-wind Movement, 26 jewels, 38 Hours Power Reserve
- 42mm Case Diameter with Polished Stainless Steel Case
- Scratch Resistant Sapphire Crystal
Alpina describes the dial as carrying a 60-minute immersion-time scale and says the rubber strap is resistant to sand, sea salt and corrosion. These are the manufacturer’s descriptions; they do not establish how the scale reads in practice or how the strap holds up over time. The page does not provide a basis for claiming tested legibility, lume performance, timing accuracy, reserve, comfort or diving performance.
What changes with the date-equipped AL-525?
The AL-525S4H6 has a date function and an internal rotating 60-minute bezel, according to Alpina’s UK product page. That page also mentions a screw-down crown, engraved caseback, textured rubber strap and a wooden box with a history plaque. Alpina’s international product page says the AL-525 is based on the SW200, beats at 28,800 alternations per hour, has 26 jewels and a stated 38-hour power reserve. These movement details apply to the AL-525 listing; they should not be assumed for the AL-520.
Rank #2
- The Alpina Seastrong Diver 300 Heritage is the ultimate automatic dive watch, water resistant to 300M and measuring immersion time up to 60 minutes.
- The 42mm stainless steel case features a green sunray dial with luminous silver colored hands.
- The stainless steel caseback is engraved with Alpinas beloved Alps and a trident, and is anchored to a green rubber strap that is sand, sea salt- and corrosion-resistant.
- Equipped with the AL-520 automatic caliber with 38hr power reserve.
Alpina positions the Heritage design as a reissue inspired by 1960s professional diver watches. That is the brand’s description of its design lineage, not independent historical verification. The available product information does not establish how either reference wears or performs compared with an original model.
Can you treat it as a 300-metre dive watch?
Alpina states 300 m/30 bar water resistance for both references discussed here. No independent water-resistance test is established by the available evidence, so the rating should be read as Alpina’s published specification rather than a separately verified result. A stated rating alone does not document the condition of an individual watch, its seals, or its suitability for a particular dive.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Rank #3
- Water-resistant to 300M, this 42mm Seastrong Diver 300 Heritage Automatic with steel case lets you measure your immersion time in hours, minutes and seconds. Its black lacquered sunray-brushed dial features gold plated luminescent hands, making it easy to read, even in the low light of the deep sea. Featuring a modern automatic caliber with 38 hours power reserve and an anti-scratch sapphire glass. Comes with two straps, one in brown calfskin leather and the other in beige topstitched rubber.
- Hours, Minutes, Seconds
- Silver-Tone Stainless Steel
- Anti-Reflective Sapphire Crystal
- 30 Meters and 3 Year Limited Warranty
The official listing mentions a screw-down crown for the AL-525S4H6. Do not assume a particular operating procedure or service interval from that feature alone; follow the instructions supplied with the exact watch and have its water resistance checked by a qualified service provider when appropriate.
Is the listed price current or comparable across markets?
On 2026-10-07, Alpina’s U.S. listings showed $1,995 for both the AL-520GR4H6 and AL-525S4H6; Alpina’s UK listing showed £1,595 for the AL-525S4H6. These are observations from the respective regional product pages on that date, not a current-price guarantee. Check the official listing for the correct reference and market before making a purchase decision.
Rank #4
- The Seastrong Diver Extreme Automatic is housed in a 39 x 40.50mm steele case and features three central hand-polished hands that sit at the heart of a dial textured with Alpina's iconic triangular emblem, punctuated by a date window at 6 o'clock.
- For maximum readability, both the hours and minutes hands and the hour markers have been coated with luminous material and the date window features black figures on a white background.
- WR to 300m, and comes on a bright orange rubber strap.
What to verify before buying
- Reference: confirm AL-520GR4H6 for the green no-date configuration or AL-525S4H6 for the date-equipped variant.
- Bezel and dial configuration: check the actual product listing and photographs; the AL-525 listing specifies an internal rotating bezel, while Alpina describes a 60-minute immersion-time scale on the AL-520.
- Fit: the published 21 mm lug width is useful when considering another strap, but width alone does not confirm that a replacement’s attachment shape and dimensions will fit.
- Seller and stock: availability and prices can change. Confirm the seller, exact reference and return terms with the retailer; a model name alone is not enough to verify a listing.
- Condition and water use: the stated water-resistance rating is not an inspection of a particular pre-owned watch. Ask for service and pressure-test documentation if buying used and planning water exposure.
Verdict
The Alpina Seastrong Diver Heritage is best assessed reference by reference. The green AL-520GR4H6 is the no-date option with Alpina-published 42 mm by 12.3 mm dimensions, a 21 mm lug width and a 38-hour stated reserve. The AL-525S4H6 adds a date and an internal rotating bezel, and has more movement detail published by Alpina. Without independent testing, neither the specifications nor the brand’s 300 m rating answer the practical questions of fit, legibility, accuracy or real-world diving use.
Quick Recap
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.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →
