Side by side

Seiko Prospex SeavsSinn U18

The numbers, the dial colors, the calibers — laid out so you can stop flipping between tabs.

Prospex Sea
SeikoProspex Sea
U18
SinnU18
MSRP $3,488
What people say

Owners + reviewers, side by side

Synthesized for each watch independently from owner discussions, enthusiast forums, written reviews, and video reviewers.

Seiko Prospex Sea

Owners widely praise the Seiko Prospex Sea for its excellent value, solid build, and comfortable wearability, with specific mentions of its matte black dial, excellent lume, and cushion case that wears smaller than its dimensions suggest. The 4R36 movement is noted for hacking and hand-winding capabilities, and the bezel action is described as smooth and precise. Some owners find the watch to be a legitimate tool with a fair price, while others describe it as big, thick, and heavy, uncomfortable for smaller wrists, though this is subjective as one owner found the size perfect. The solar quartz movement is also highlighted as a collection-worthy feature. On balance, owners and reviewers rate the Seiko Prospex Sea highly for its exceptional value and comfortable, classic design.

Sinn U18

The Sinn U18 is praised for its unique deep blue/green dial with three-dimensional oxygen bubbles that change with light, and its comfortable, easily adjustable bracelet. Owners find the watch stunning and a piece of history, appreciating the refined hands. The Sinn U18 features a 44mm, 15.5mm thick case made from German submarine steel, offering a 2000-meter dive specification and Sinn's Ar-Dehumidifying technology, powered by a Sellita SW300-1 movement. The case thickness is apparent, and the watch comes as a complete set with box and papers for $3,000-$3,680. On balance, owners and reviewers rate the Sinn U18 highly for its striking dial and robust build.

At a glance

16 of 29 specs differ
Diameter
Prospex Sea42mm
U1844mm
Power Reserve
Prospex Sea72h
U1842h
Water Resistance
Prospex Sea300m
U182,000m
MSRP
Prospex Sea
U18$3,488

Full specifications

Case

8 specs
Diameter
42mm
44mm
Thickness
13.3mm
15.5mm
Lug-to-Lug
48.6mm
Lug Width
20mm
22mm
Material
Stainless Steel
high-strength
Finish
Brushed and polished
Water Resistance
300m
2000m
Caseback
Solid

Crystal & Dial

4 specs
Crystal Shape
Flat
AR Coating
Anti-reflective coating on inner surface
Indices
Applied
Lume
LumiBrite on hands, index(es) and bezel
None

Movement

3 specs
Caliber
6R54
SW300-1
Power Reserve
72h
42h
Jewels
24
25

Pricing

1 specs
MSRP
$3,488
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