Seiko Orange Monster Dive Watch

[brewthunda]

You do time your dives, right? And I assume diving time is VERY dependent on your air supply? So therefore, you are in a way keeping track of your air with a watch? QED.

Diving time is dependent on your nitrogen saturation, which is based on how deep you go and for how long. You're timing yourself so that you don't get the bends, not to monitor your air supply. You also use air at different rates based on how deep you dive. At depth you're breathing highly compressed air at a similar breathing pace, so you wind up breathing a lot more air than on a shallow dive. Hence, timing is not consistent from dive to dive. If you tried to "time" your air using a watch, you'd probably die within a couple of dives. You keep track of your air with an air gauge.