What's the story?
Umpteen iconic dive watches emerged from the 1960s, but it wasn't until 1971 that horology got its first legendary chronograph, the Omega Seamaster 120m Automatic Chronograph (or SM120c for short). It was a serious piece of diving kit and cost a bloomin' packet, which is why it was only produced until 1973.
Why should I want one?
Because it's rare and awesome looking. Check out the shrouded strap lugs and that gorgeous blue dial and bezel, which earns it the nickname "Big Blue". It also offers some of the size and wrist presence of the Seamaster "PloProf" without so much of the love-it-or-hate-it styling. The case is an imposing 44m wide and 17mm thick, which is big even by today's standards.
What to look for
The Omega Calibre 1040 automatic movement (based on the respected Lemania 1340) will need servicing, if it hasn't already been checked over in recent years. If the bezel's in poor condition, good luck finding a replacement – just enjoy it in its "lovingly used" state. Expect to pay around £3000 for one in good condition. If it's recently been restored by Omega at the Bienne workshop or Swiss Time Services in the UK, you might even get a valid warranty with it. For more in-depth details and pics, head to Desk Divers.