Updated
Seiko Prospex "Turtle" vs Tudor Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet)
Two divers compared — $500–$1,000 vs $2,500–$5,000
Quick Verdict
The Seiko Prospex "Turtle" ($500–$1,000) offers In-House Automatic Manufacture precision in the tier below the Tudor Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) ($2,500–$5,000). The Prospex "Turtle" measures 45mm and is rated 200m (20 ATM) Diver. The Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) counters with Swiss Made craftsmanship and 200m (20 ATM) water resistance. Both are exceptional divers for their respective tiers.
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Tudor
Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet)
$2,500–$5,000
Specifications Compared
| Feature | Seiko Prospex "Turtle" | Tudor Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) |
|---|---|---|
| Price | $500–$1,000 | $2,500–$5,000 |
| Case Size | 45mm | 37mm, 11.2mm thick, 20mm lugs |
| Movement | Automatic Caliber 4R36 | Tudor manufacture calibre MT5400, automatic, COSC chronometer, bidirectional rotor |
| Caliber Type | In-House Automatic Manufacture | Tudor manufacture MT5400, COSC |
| Power Reserve | 41 Hours | About 70 hours |
| Water Resistance | 200m (20 ATM) Diver | 200m (20 ATM) |
| Crystal | Sapphire Crystal | Domed sapphire |
| Case Material | Stainless Steel | Stainless steel, polished and satin; 60-minute unidirectional steel bezel with aluminium insert devoid of minute graduations; screw-down crown |
| Origin | Made in Japan | Swiss Made |
Category-by-Category Analysis
Design & Aesthetics
Seiko's design language vs Tudor's approach
The Seiko Prospex "Turtle" features a Stainless Steel case at 45mm with Sapphire Crystal protection. The Tudor Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) offers Stainless steel, polished and satin; 60-minute unidirectional steel bezel with aluminium insert devoid of minute graduations; screw-down crown construction at 37mm, 11.2mm thick, 20mm lugs with Domed sapphire. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Automatic Caliber 4R36 vs Tudor manufacture calibre MT5400, automatic, COSC chronometer, bidirectional rotor
The Prospex "Turtle" runs the Automatic Caliber 4R36 (In-House Automatic Manufacture, 41 Hours power reserve) at 21,600 vph (3 Hz) frequency. The Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) uses the Tudor manufacture calibre MT5400, automatic, COSC chronometer, bidirectional rotor (Tudor manufacture MT5400, COSC, About 70 hours reserve) at standard. The Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) offers a longer power reserve.
Wearability & Fit
45mm vs 37mm, 11.2mm thick, 20mm lugs — different wrist presence
At 45mm, the Prospex "Turtle" has a bolder wrist presence compared to the Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) at 37mm, 11.2mm thick, 20mm lugs. Water resistance differs: 200m (20 ATM) Diver vs 200m (20 ATM).
Value & Cost of Ownership
Seiko sits in the lower tier
The Seiko Prospex "Turtle" sits at $500–$1,000 and the Tudor Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) at $2,500–$5,000. On the specs that outlast any price: the Prospex "Turtle" uses Sapphire Crystal with 41 Hours, against Domed sapphire and About 70 hours on the Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet). Service intervals are typically 5-7 years for both.
Water Resistance
200m (20 ATM) Diver vs 200m (20 ATM)
The Prospex "Turtle" is rated to 200m (20 ATM) Diver while the Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) handles 200m (20 ATM). Both offer identical water resistance ratings.
Our Verdict
Seiko
Prospex "Turtle"
Choose the Seiko Prospex "Turtle" if you prioritize In-House Automatic Manufacture engineering, Made in Japan craftsmanship, and 200m (20 ATM) Diver water resistance. At $500–$1,000, it delivers Automatic Caliber 4R36 with 41 Hours power reserve.
Check Price on AmazonTudor
Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet)
Choose the Tudor Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) if you value Tudor manufacture MT5400, COSC technology, Swiss Made heritage, and 37mm, 11.2mm thick, 20mm lugs proportions. At $2,500–$5,000, the Tudor manufacture calibre MT5400, automatic, COSC chronometer, bidirectional rotor with About 70 hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Seiko Prospex "Turtle" and Tudor Black Bay 54 37mm M79000N-0001 (steel, black bezel and dial, steel bracelet) represent two distinct approaches to the diver category — the Seiko bringing Made in Japan tradition while Tudor 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.