Spinnaker Spence 300vsSeiko 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.

Spence 300

Prospex Sea
Diameter
40mm
41.7mm
Lug-to-Lug
48mm
lowest
49.5mm
Thickness
11.5mm
lowest
12.3mm
Water Resistance
300m
highest
200m
Power Reserve
n/a
41h
MSRP
$650
$595
lowest
Movement
Seiko NH35
Seiko 4R35
Case
5 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 Spinnaker Spence 300 for its slim 10.9mm case and 40mm diameter, offering a comfortable and versatile wear. Reviewers and owners alike highlight its value, with some seeing it as a budget alternative to more expensive dive watches. The watch features a Seiko NH35 automatic movement and 300m water resistance. However, some community members find the dial printing and bracelet finishing to be less refined, and a few suggest other brands offer better value at similar price points. On balance, owners and reviewers rate the Spinnaker Spence 300 highly for its impressive case dimensions and overall value proposition.
The watch's thin 10.9mm profile for a 300m diver is a key strength. No shared weakness was identified.
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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