Side by side

Borealis Watch Co. Estoril 300 GMTvsSeiko Prospex Sea

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

Estoril 300 GMT
Borealis Watch Co.Estoril 300 GMT
MSRP $600
Prospex Sea
SeikoProspex Sea
MSRP $1,100
What people say

Owners + reviewers, side by side

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

Borealis Watch Co. Estoril 300 GMT

Owners widely praise the Borealis Watch Co. Estoril 300 GMT for its excellent value, robust build quality, and crisp dial, with reviewers highlighting its exceptionally bright BGW9 lume and dive-ready ceramic bezel. Some owners appreciate the brushed and polished finishes, though one owner noted a desire for a white-painted second hand. The included NATO strap is considered too thick with a loose weave, and the sapphire bezel insert is seen by some as a minor aesthetic departure from its inspirations. Overall, owners rate the Borealis Watch Co. Estoril 300 GMT highly for its impressive build quality and value.

Seiko Prospex Sea

Seiko Prospex Sea models are widely praised for their excellent build quality, value for money, and comfortable wearability, with many appreciating the vintage-inspired designs and robust construction. Owners note the silicone straps are surprisingly comfortable and well-finished, and the Lumibrite lume is excellent. However, some find the 44.3mm size and thickness too large for smaller wrists, though others report the sizing as perfect. The 6R15 movement in some variants offers accuracy around +4 seconds per day with a 50-hour power reserve, while newer movements offer more. Some models are criticized for a bracelet width not matching the case size or a rudimentary clasp for their price point. Overall, owners and reviewers rate the Seiko Prospex Sea highly for its impressive case work and finishing at its price point.

At a glance

10 of 29 specs differ
Diameter
Estoril 300 GMT41.50mm
Prospex Sea41.3mm
Power Reserve
Estoril 300 GMT40h
Prospex Sea72h
Water Resistance
Estoril 300 GMT300m
Prospex Sea300m
MSRP
Estoril 300 GMT$600
Prospex Sea$1,100

Full specifications

Case

4 specs
Diameter
41.50mm
41.3mm
Thickness
13.5mm
12.5mm
Lug-to-Lug
47mm
48.2mm
Lug Width
20mm
20mm

Crystal & Dial

2 specs
AR Coating
Inner
Anti-reflective coating on inner surface
Lume
BGW9
LumiBrite on hands, index(es) and bezel

Movement

3 specs
Caliber
Miyota 9075
6R55
Power Reserve
40h
72h
Jewels
25
24

Pricing

1 specs
MSRP
$600
$1,100
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