Casio Pro Trek PRG340-1 vs Seiko Prospex "Turtle"
Casio's timepiece meets Seiko's diver
Quick Verdict
The Casio Pro Trek PRG340-1 ($150–$250) offers Tough Solar Quartz (No Battery Change) precision in the tier below the Seiko Prospex "Turtle" ($500–$1,000). The Pro Trek PRG340-1 measures 54.7 × 51.7 × 15.1mm and is rated 100m (10 ATM). The Prospex "Turtle" counters with Made in Japan craftsmanship and 200m (20 ATM) Diver water resistance. Both are exceptional watches for their respective tiers.
Transparency — We earn a small commission on purchases made through our Amazon links. This doesn't affect our editorial independence.
Specifications Compared
| Feature | Casio Pro Trek PRG340-1 | Seiko Prospex "Turtle" |
|---|---|---|
| Price | $150–$250 | $500–$1,000 |
| Case Size | 54.7 × 51.7 × 15.1mm | 45mm |
| Movement | Tough Solar (Solar Quartz) | Automatic Caliber 4R36 |
| Caliber Type | Tough Solar Quartz (No Battery Change) | In-House Automatic Manufacture |
| Power Reserve | Tough Solar (Rechargeable) | 41 Hours |
| Water Resistance | 100m (10 ATM) | 200m (20 ATM) Diver |
| Crystal | Mineral Glass | Sapphire Crystal |
| Case Material | Bio-Based Resin | Stainless Steel |
| Origin | Casio (Japan) | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Casio's design language vs Seiko's approach
The Casio Pro Trek PRG340-1 features a Bio-Based Resin case at 54.7 × 51.7 × 15.1mm with Mineral Glass 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
Tough Solar (Solar Quartz) vs Automatic Caliber 4R36
The Pro Trek PRG340-1 runs the Tough Solar (Solar Quartz) (Tough Solar Quartz (No Battery Change), Tough Solar (Rechargeable) power reserve) at standard frequency. The Prospex "Turtle" uses the Automatic Caliber 4R36 (In-House Automatic Manufacture, 41 Hours reserve) at 21,600 vph (3 Hz). The Prospex "Turtle" offers a longer power reserve.
Wearability & Fit
54.7 × 51.7 × 15.1mm vs 45mm — different wrist presence
At 54.7 × 51.7 × 15.1mm, the Pro Trek PRG340-1 has a bolder wrist presence compared to the Prospex "Turtle" at 45mm. Water resistance differs: 100m (10 ATM) vs 200m (20 ATM) Diver.
Value & Cost of Ownership
Casio sits in the lower tier
The Casio Pro Trek PRG340-1 sits at $150–$250 and the Seiko Prospex "Turtle" at $500–$1,000. On the specs that outlast any price: the Pro Trek PRG340-1 uses Mineral Glass with Tough Solar (Rechargeable), against Sapphire Crystal and 41 Hours on the Prospex "Turtle". Service intervals are typically 5-7 years for both.
Water Resistance
100m (10 ATM) vs 200m (20 ATM) Diver
The Pro Trek PRG340-1 is rated to 100m (10 ATM) while the Prospex "Turtle" handles 200m (20 ATM) Diver. The Prospex "Turtle" offers superior water resistance.
Our Verdict
Casio
Pro Trek PRG340-1
Choose the Casio Pro Trek PRG340-1 if you prioritize Tough Solar Quartz (No Battery Change) engineering, Casio (Japan) craftsmanship, and 100m (10 ATM) water resistance. At $150–$250, it delivers Tough Solar (Solar Quartz) with Tough Solar (Rechargeable) 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 Casio Pro Trek PRG340-1 and Seiko Prospex "Turtle" represent two distinct approaches to fine watchmaking — the Casio bringing Casio (Japan) tradition while Seiko delivers Made in Japan engineering.
Frequently Asked Questions
More Comparisons
Explore These Watches
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.