Watch Almanac
Seiko

Prospex 1970 Diver's Modern Re-interpretation

Ref. SPB317 · “Captain Willard”

Case diameter
41 mm
Manufacturer spec
Lug-to-lug
46.9 mm
Manufacturer spec
Thickness
12.3 mm
Manufacturer spec
Lug width
20 mm
Manufacturer spec

Retail price $900 (US, Oct 2026)

Ideal fit
Wrist flat: 55.1 mmLug-to-lug: 46.9 mm

How the Prospex 1970 Diver's Modern Re-interpretation wears

Its lugs add 5.9 mm to the 41 mm case, close to the 7.1 mm typical across the almanac, so its diameter is a fair guide to how it wears.

On our fit model it sits best on wrists from 6.5" to 7.75" (16.5–19.7 cm); below 6.5" the lugs start to reach the edge of the wrist.

At 12.3 mm thick it is slimmer than 75% of the 79 other dive watches we've measured, so it slides under a cuff more easily than most.

Its 20 mm lug width is one of the most common strap sizes; 104 other watches here share it, so aftermarket straps are easy to find.

Will the Prospex 1970 Diver's Modern Re-interpretation fit your wrist?

With a 46.9 mm lug-to-lug, here is how it wears across common wrist sizes. We estimate the flat top of each wrist from its circumference; measure yours for a closer answer in the fit finder.

WristFlat width (est.)Fit
6"47.2 mmLugs overhang
6.5"51.2 mmIdeal fit
7"55.1 mmIdeal fit
7.5"59.1 mmIdeal fit
8"63 mmWears small

Specifications

Reference
SPB317
Collection
Prospex
Status
In production
Case material
stainless steel
Crystal
curved sapphire
Water resistance
200 m
Bezel
unidirectional rotating 60-minute diver's bezel
Dial
black
Strap / bracelet
black silicone strap
Weight
100 g
Style
Dive

Movement

Caliber
Seiko 6R35
Type
automatic
Power reserve
70 hours
Frequency
21,600 vph (3 Hz)
Jewels
24
Accuracy
+25/-15 s/day

6 other watches use the Seiko 6R35

Takes 20 mm straps. See other 20 mm watches and straps.

More Prospex references

Watches that wear the same size

Other watches within 1.5 mm of its lug-to-lug.

Same 20 mm lug width

All 20 mm watches

These take the same straps as the Prospex 1970 Diver's Modern Re-interpretation.

Sources