Side by side

Serica Ref. 5303 Diving ChronometervsSeiko Prospex Sea

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

Ref. 5303 Diving Chronometer
SericaRef. 5303 Diving Chronometer
MSRP $1,768
Prospex Sea
SeikoProspex Sea
MSRP $900

At a glance

13 of 29 specs differ
Diameter
Ref. 5303 Diving Chronometer39mm
Prospex Sea41mm
Power Reserve
Ref. 5303 Diving Chronometer42h
Prospex Sea70h
Water Resistance
Ref. 5303 Diving Chronometer300m
Prospex Sea200m
MSRP
Ref. 5303 Diving Chronometer$1,768
Prospex Sea$900

Full specifications

Case

4 specs
Diameter
39mm
41mm
Thickness
12.2mm
12.3mm
Lug-to-Lug
46.5mm
46.9mm
Water Resistance
300m
200m

Crystal & Dial

4 specs
Crystal Shape
Flat
Curved
AR Coating
Yes
Anti-reflective coating on inner surface
Dial Color
Enamel Black
Black
Lume
Super-LumiNova
LumiBrite on hands, index(es) and bezel

Movement

4 specs
Caliber
M100 COSC
6R35
Power Reserve
42h
70h
Jewels
25
24
Complications
COSC
None

Pricing

1 specs
MSRP
$1,768
$900

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What people say

Owners + reviewers, side by side

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

Serica Ref. 5303 Diving Chronometer

Owners widely praise the Serica Ref. 5303 Diving Chronometer for its excellent wearability, definitive style, and smooth, confident bezel action. The dual scale on the bezel is noted as surprisingly useful, and the crown action, winding, and hacking are reported to work perfectly. One owner describes the Serica 5303-3 as gorgeous and unique, though another notes the crown can appear comically large. On balance, owners rate the Serica Ref. 5303 Diving Chronometer highly for its blend of unique design and robust functionality.

Seiko Prospex Sea

Owners widely praise the Seiko Prospex Sea for its excellent lume, robust build, and value, with many highlighting the comfortable 4 o'clock crown and reliable movements. Reviewers note impressive case finishing and attractive dials, with specific models lauded for their gradient blue designs and smooth bezel actions. Accuracy figures vary, with one owner reporting +9 seconds/day after demagnetization, while others find the watches to be good first "proper" watches. Some owners find the stock rubber straps uncomfortable or the overall size substantial on smaller wrists. On balance, owners and reviewers rate the Seiko Prospex Sea highly for its combination of strong dive watch functionality and appealing design at its price point.

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