I have the Black Cream model. Absolutely love it. 

Mine measures 13mm with my caliper.  Their website says 12mm, but that's not what I see.

No matter to me...great watch.

I have one too. I really like it except for two quality control issues - there are several flecks of white dust on the subdials, and the timer hand does not line up precisely with the indexes.

Since this is not a budget watch I expect better.

The Aquascaphe is a fantastic piece. I have the black cream version on the Baltic tropic rubber strap. Looks & feels great. Perfect size for me. Love the subdued, no-bling, heritage look.
https://i.imgur.com/1hWE8ak.jpg
(edit: oops...I expected my Imgur photo to embed here. Click on link to see my Aquascaphe)