Longines HydroConquest Automatic vs Seiko Prospex "Turtle"
Two divers compared — $1,500–$2,500 vs $500–$1,000
Quick Verdict
The Seiko Prospex "Turtle" ($500–$1,000) delivers In-House Automatic Manufacture technology in the tier below the Longines HydroConquest Automatic ($1,500–$2,500). The Prospex "Turtle" measures 45mm and is rated 200m (20 ATM) Diver. 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 | Seiko Prospex "Turtle" |
|---|---|---|
| Price | $1,500–$2,500 | $500–$1,000 |
| Case Size | 41mm | 45mm |
| Movement | Automatic L888.5 | Automatic Caliber 4R36 |
| Caliber Type | ETA-Based Automatic with Silicon Balance Spring | In-House Automatic Manufacture |
| Power Reserve | 72 Hours | 41 Hours |
| Water Resistance | 300m (30 ATM) | 200m (20 ATM) Diver |
| Crystal | Sapphire with Anti-Reflective Coating | Sapphire Crystal |
| Case Material | Stainless Steel | Stainless Steel |
| Origin | Swiss Made | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Longines's design language vs Seiko's approach
The Longines HydroConquest Automatic features a Stainless Steel case at 41mm with Sapphire with Anti-Reflective Coating protection. The Seiko Prospex "Turtle" offers Stainless Steel construction at 45mm with Sapphire Crystal. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Automatic L888.5 vs Automatic Caliber 4R36
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 Prospex "Turtle" uses the Automatic Caliber 4R36 (In-House Automatic Manufacture, 41 Hours reserve) at 21,600 vph (3 Hz). The HydroConquest Automatic edges ahead on power reserve.
Wearability & Fit
41mm vs 45mm — different wrist presence
At 41mm, the HydroConquest Automatic wears more compactly on smaller wrists compared to the Prospex "Turtle" at 45mm. Water resistance differs: 300m (30 ATM) vs 200m (20 ATM) Diver.
Value & Cost of Ownership
Seiko sits in the lower tier
The Longines HydroConquest Automatic sits at $1,500–$2,500 and the Seiko Prospex "Turtle" at $500–$1,000. On the specs that outlast any price: the HydroConquest Automatic uses Sapphire with Anti-Reflective Coating with 72 Hours, against Sapphire Crystal and 41 Hours on the Prospex "Turtle". Service intervals are typically 5-7 years for both.
Water Resistance
300m (30 ATM) vs 200m (20 ATM) Diver
The HydroConquest Automatic is rated to 300m (30 ATM) while the Prospex "Turtle" handles 200m (20 ATM) Diver. The HydroConquest Automatic is better suited for water activities.
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 AmazonSeiko
Prospex "Turtle"
Choose the Seiko Prospex "Turtle" if you value In-House Automatic Manufacture technology, Made in Japan heritage, and 45mm proportions. At $500–$1,000, the Automatic Caliber 4R36 with 41 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Longines HydroConquest Automatic and Seiko Prospex "Turtle" represent two distinct approaches to the diver category — the Longines bringing Swiss Made tradition while Seiko delivers Made in Japan 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.