Watch dials

[237SJ]

What is that rotating dial with numbers on Rolex watches for? Is it for divers to mark their depth?

[Count-A-Strong]

Analog diving watches will often feature a rotating bezel, that allows for an easier reading of elapsed time of under one hour from a specific point. This is used to compute the length of a dive. (See Tachymeter.) When the zero on the bezel is aligned with the watch's seconds or (usually) minutes hand on the water entry moment a diver can read off the elapsed time from the bezel.

[237SJ]

Thanks Count. I was admiring the Rolex Yachtmaster and it has one of those dials. If it`s a "yachty" watch, I can`t really see the point of it. It must be a gimmick.