In an Undercurrent article three years ago, we poohpoohed
the idea of buying a dive watch when dive
computers have more features and are way less expensive.
However, we did advise that if you have an old
dive watch lying around, you should consider selling it.
They're more commonly being appreciated as valuable
collectibles, and watch collectors, whether scuba divers
or not, are shelling out more money for them.
Take this Breguet diver's watch that hit the auction
  block at Christies last month. According to Luke
  Rottman, executive editor of the Watch Adviser blog,
  20th century Breguet wristwatches are the rarest watches
  on earth. In 1962, Breguet produced roughly 60 dive watches, all with varying dials. "Hence, this [watch]with
  an Arabic dial, to the best of my knowledge, is likely
  piece-unique," says Rottman. It's similar to "tool watches"
  (those designed for specific purposes, like diving or
  flying) of the 1950s, such as the Rolex 6536 Submariner
  and the Blancpain Fifty Fathoms, but not that innovative
  compared to larger dive watches that Blancpain, Omega,
  Eberhard, and Rolex were already beginning to produce.
  But according to Rottman, it's all about the aesthetics.
Christie originally estimated this Breguet's value
  as between $32,000 and $65,000. Rottman sniffed, saying
  that wasn't the least bit generous. "If anything, this
  watch will fetch a considerably higher dollar amount
  than what Christie's anticipates." And he was right -- the
  world's rarest dive watch ultimately sold for $100,866.
  So if you have an old dive watch, get thee to a jewelry
  appraiser post haste.