My collection. I really like all of these watches very much and I wear them each week except for the Speedmaster which I only take out for special occasions.

 

What is the purpose of that vent on the far right watch?

 

The watch is a Citizen Aqualand, the first watch with a built-in depth gauge. The vent is for the pressure sensor. The Aqualand was introduced in 1986. Here's a nice review of this classic:

https://monochrome-watches.com/citi...the-blue-collar-dive-watch-from-japan-review/

 

Cool collection of classics! Every one’s a Winner

 

3 beautiful watches, both others I could live without.