Marathon Arctic OSAR 41mm AutomaticvsSeiko Prospex Sea
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Measurements
Catalog photos are all shot at the same flattering size. These aren't: every case below shares one millimeter scale.

Arctic OSAR 41mm Automatic

Prospex Sea
Diameter
41mm
41.7mm
Lug-to-Lug
43.5mm
lowest
49.5mm
Thickness
13mm
12.3mm
lowest
Water Resistance
300m
highest
200m
Power Reserve
n/a
41h
MSRP
$1,800
$595
lowest
Movement
Sellita SW220-1
Seiko 4R35
Case
6 specsCrystal & Dial
3 specsMovement
3 specsPricing
1 specsReviews
Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.
Owners widely praise the Marathon Arctic OSAR 41mm Automatic for its comfortable wearability, with one owner noting it feels lightweight and wears perfectly on a sub-7-inch wrist. The watch is designed for legibility, featuring oversized hour markers as a tool watch. Accuracy observations vary, with one owner reporting a consistent +1 second per day, while another noted -20 seconds per day. The bracelet is described as lacking refinement, with no quick-release or toolless micro-adjustment. On balance, owners and reviewers appreciate the Marathon Arctic OSAR 41mm Automatic for its tool-watch legibility and comfortable wear, though some question its value at the current price point.
Owners widely report the Seiko Prospex Sea is a well-built watch at a fair price, with some finding its 41.7mm case size perfect while others with smaller wrists consider it big, thick, and heavy. Reviewers consistently praise the excellent lume and robust design. One owner notes the bezel action is smoother and more precise than some other Seiko divers. Overall, owners and reviewers rate the Seiko Prospex Sea highly for its value and proven design.
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