Longines HydroConquest Automatic vs Mido Ocean Star GMT
Two divers compared — $1,500–$2,500 vs $1,000–$1,500
Quick Verdict
The Mido Ocean Star GMT ($1,000–$1,500) delivers Automatic (ETA C07.661 base) technology in the tier below the Longines HydroConquest Automatic ($1,500–$2,500). The Ocean Star GMT measures 44mm and is rated 200m (20 ATM). The HydroConquest Automatic justifies its premium with Swiss Made heritage and Automatic L888.5. Both represent excellent choices in the diver category.
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Specifications Compared
| Feature | Longines HydroConquest Automatic | Mido Ocean Star GMT |
|---|---|---|
| Price | $1,500–$2,500 | $1,000–$1,500 |
| Case Size | 41mm | 44mm |
| Movement | Automatic L888.5 | Automatic Caliber 80 (Base ETA C07.661) |
| Caliber Type | ETA-Based Automatic with Silicon Balance Spring | Automatic (ETA C07.661 base) |
| Power Reserve | 72 Hours | 80 Hours |
| Water Resistance | 300m (30 ATM) | 200m (20 ATM) |
| Crystal | Sapphire with Anti-Reflective Coating | Sapphire with Double-sided AR |
| Case Material | Stainless Steel | Stainless Steel |
| Origin | Swiss Made | Swiss Made |
Category-by-Category Analysis
Design & Aesthetics
Longines's design language vs Mido's approach
The Longines HydroConquest Automatic features a Stainless Steel case at 41mm with Sapphire with Anti-Reflective Coating protection. The Mido Ocean Star GMT offers Stainless Steel construction at 44mm with Sapphire with Double-sided AR. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Automatic L888.5 vs Automatic Caliber 80 (Base ETA C07.661)
The HydroConquest Automatic runs the Automatic L888.5 (ETA-Based Automatic with Silicon Balance Spring, 72 Hours power reserve) at 25,200 vph (3.5 Hz) frequency. The Ocean Star GMT uses the Automatic Caliber 80 (Base ETA C07.661) (Automatic (ETA C07.661 base), 80 Hours reserve) at 21,600 vph (3 Hz). The Ocean Star GMT offers a longer power reserve.
Wearability & Fit
41mm vs 44mm — different wrist presence
At 41mm, the HydroConquest Automatic wears more compactly on smaller wrists compared to the Ocean Star GMT at 44mm. Water resistance differs: 300m (30 ATM) vs 200m (20 ATM).
Value & Cost of Ownership
Mido sits in the lower tier
The Longines HydroConquest Automatic sits at $1,500–$2,500 and the Mido Ocean Star GMT at $1,000–$1,500. On the specs that outlast any price: the HydroConquest Automatic uses Sapphire with Anti-Reflective Coating with 72 Hours, against Sapphire with Double-sided AR and 80 Hours on the Ocean Star GMT. Service intervals are typically 5-7 years for both.
Water Resistance
300m (30 ATM) vs 200m (20 ATM)
The HydroConquest Automatic is rated to 300m (30 ATM) while the Ocean Star GMT handles 200m (20 ATM). The HydroConquest Automatic is better suited for water activities.
Materials Face-Off
| Component | Longines HydroConquest Automatic | Mido Ocean Star GMT |
|---|---|---|
| Ceramic Bezel | Zirconium oxide (ZrO₂) with engraved and paint-filled 60-minute dive scale Mohs 8.5 | Stainless steel 316L |
| Sapphire Crystal | Flat sapphire with anti-reflective coating on the underside Mohs 9 | Synthetic sapphire grown via Verneuil process, Mohs 9. Double-sided AR coating — uncommon at this price tier, provides exceptionally clear dial readi Mohs 9 |
| Silicon Balance Spring | Si hairspring in the L888.5 caliber — introduced 2020 across the HydroConquest line | Ceramic (ZrO₂) — scratchproof, color-stable. Engraved 24-hour scale |
| 316L Stainless Steel | Brushed flanks with polished bevel edges — mixed finishing for visual depth | Super-LumiNova (variant-dependent grade) |
| Super-LumiNova | Applied to sword-style hands and all hour indices | Stainless steel 316L |
Cost of Ownership Compared
The Mido Ocean Star GMT saves you $641 over 5 years of ownership
Who Should Pick Which
Pick the Longines HydroConquest Automatic if…
- Best-in-class 72-hour power reserve at sub-$2,000
- Silicon hairspring antimagnetic protection at an accessible price
- Swiss heritage enthusiasts — Longines' 1832 founding and Olympic/aviation history
- Legitimate 300m dive capability with everyday wearability
- Value seekers — at grey-market pricing the spec-per-dollar is nearly unbeatable
Pick the Mido Ocean Star GMT if…
- Enthusiasts wanting proven Swiss/Japanese quality in the $1,000–$2,000 sweet spot
- Dive watch enthusiasts — 200m water resistance is proper dive spec
- Weekend warriors — 80-hour power reserve means it survives two days off the wrist
- Those who prioritize scratch resistance — sapphire crystal
- Dive watch collectors who appreciate proper ISO-rated tool watches
Longines HydroConquest Automatic
- ETA-base movement at this price — excellent but not "in-house" in the purist sense
- 21mm lug width — awkward for aftermarket straps (most are 20mm or 22mm)
- 25,200 vph (3.5 Hz) — seconds hand sweep is less smooth than 28,800 vph competitors
- Not COSC-certified — no chronometer guarantee (unlike Tudor or Omega at similar prices)
Mido Ocean Star GMT
- 44mm wears large — too big for under-7" wrists
- ETA base movement at this price — fair value but not in-house prestige
- Crystal AR coating can show fingerprints — double-sided AR is a quality upgrade but requires more frequent wipe-downs
- Bracelet quality is adequate not exceptional — most owners report the bracelet is the watch's weak point; aftermarket rubber/MN straps significantly upgrade daily wear
Our Verdict
Longines
HydroConquest Automatic
Choose the Longines HydroConquest Automatic if you prioritize ETA-Based Automatic with Silicon Balance Spring engineering, Swiss Made craftsmanship, and 300m (30 ATM) water resistance. At $1,500–$2,500, it delivers Automatic L888.5 with 72 Hours power reserve.
Check Price on AmazonMido
Ocean Star GMT
Choose the Mido Ocean Star GMT if you value Automatic (ETA C07.661 base) technology, Swiss Made heritage, and 44mm proportions. At $1,000–$1,500, the Automatic Caliber 80 (Base ETA C07.661) with 80 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Longines HydroConquest Automatic and Mido Ocean Star GMT represent two distinct approaches to the diver category — the Longines bringing Swiss Made tradition while Mido delivers Swiss Made engineering.
Frequently Asked Questions
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How This Page Was Made
Our comparisons are generated from a hand-maintained specification database and reviewed under our editorial standards. We use AI tools to assemble pages from that data. We don’t invent specs: every number traces back to the database, and when we correct an entry, the fix is applied site-wide. As an Amazon Associate, The Horologist earns from qualifying purchases.