Seamaster Aqua Terra 150M Co-Axial 38.5 Annual Calendar Stainless Steel / Black

In Context

At 38.5 mm it sits just under the modern norm — the band that suits the widest spread of wrists. The case back is open, so the movement is visible without taking the watch apart, and the sapphire crystal will resist everything short of deliberate abuse. 150 m is genuine swimming resistance — more than the shape of this watch suggests it would need.

The movement winds itself from the motion of your wrist. 60 hours of reserve is enough to set it down on Friday evening and find it still running on Monday. At 25,200 vph the seconds hand advances 7 times a second.

231.13.39.22.01.001 stands on its own in this catalogue — no other reference here shares its base number. It pairs a black dial with a stainless steel case. Beyond the time it carries an annual calendar.

The annual-calendar member of Omega's Co-Axial 8500 family, with the month indicated at three o'clock. It carries the full Master Chronometer specification: certified by METAS rather than only COSC, with a free-sprung balance, silicon balance spring and resistance to magnetic fields of 15,000 gauss — a level at which conventional hairsprings stop keeping time altogether. Winding is bidirectional and the reserve is 60 hours.

33 other watches in the library run the Omega 8601.

Omega

Seamaster Aqua Terra 150m Co-Axial 43 Annual Calendar Stainless Steel / Grey / Bracelet

231.10.43.22.06.001 · 43 mm

Omega

Seamaster Aqua Terra 150M Co-Axial 38.5 Annual Calendar 38.5 Stainless Steel / Silver

231.13.39.22.02.001 · 38.5 mm

Omega

Seamaster Aqua Terra 150M Co-Axial 43 Annual Calendar Stainless Steel / Red Gold / Grey / Bracelet

231.20.43.22.06.001 · 43 mm

Omega

Seamaster Aqua Terra 150M Co-Axial 38.5 Annual Calendar Stainless Steel / Red Gold / Grey / Bracelet

231.20.39.22.06.001 · 38.5 mm